14th century Jews buried in Erfurt, Germany
       One of 2022's most momentous genetic studies presented many types of data from 33 Jews who were buried in the city of Erfurt in central Germany in the mid-to-late 14th century (Waldman et al., 2022). Some of these Jews (called "Erfurt-ME") descended from the Jews of the Rhineland further to the west while others ("Erfurt-EU") were Knaanic Jews who had lived in Czechia and Poland and had spoken Slavic. Although both subgroups had Middle Eastern and Southern European roots in common, the Knaanic Jews had heavily intermarried with West Slavic converts to Judaism around the start of the 13th century, that is, about 5 generations before the Erfurt samples. Modern Ashkenazic Jews from Eastern Europe are descended from both groups but somewhat more from the Rhineland Jews (roughly a 60:40 ratio) and only a very small amount of ancestry was contributed later by Sephardic Jewish migrants and newer Polish converts.

Janice Sellers is a match
       The Erfurt sample I will focus on here, because she matches ZichronNote's former editor and many other modern people of Ashkenazic descent, has the sample code I14740 and has been uploaded to GEDmatch as kit number EJ7716177. This woman died no later than the year 1398 and her age at death is estimated to have been between 35 and 50. She had 829,090 SNPs tested, which provide decent SNP overlaps with modern Ashkenazim.

Different profile than typical for modern Ashkenazi
       In GEDmatch's Eurogenes K36 calculator, she scores a total of 29.14 percent in West Asian elements (adding up 12.52 percent East Mediterranean, 9.26 percent Near Eastern, 3.38 percent Arabian, 2.74 percent Armenian, and 1.24 percent West Caucasian), significantly less than any modern Ashkenazim. For comparison, as a full modern Eastern Ashkenazi, my total for those five elements is 39.83 percent and some Ashkenazim score several points higher than I do. Her Slavic-associated components include 4.47 percent Central European, 13.27 percent East Central European (based primarily on Belarusian, Lithuanian, and Ukrainian reference samples), and zero percent Eastern European whereas mine are only 2.75, 5.01, and 0.71 respectively.
       Her mtDNA haplogroup, N9a3a1b1, still extant in today's Eastern Ashkenazi population (GenBank sample OQ732365 from my data set), is identified in the study as being "nested within a Central/East Asian branch" in part because its parent subclade, N9a3a1b, is found among Turkic-speaking Bashkirs from the Ural Mountains area (BioProject samples SRS6892124 and SRS6892238 from the data set of Nagy et al. 2021) and Mongolic-speaking Daurs from northeastern China (GenBank sample ON127764 from the data set of Jia et al. 2022). Simultaneously, she carries higher-than-average total Khazar-associated elements for a Jew: 2.1 percent East Central Asian (based on Daurs and other Mongolic and Tungusic peoples) plus 4.04 percent Volga-Ural (based on Turkic-speaking Chuvash reference samples) but no amount of Siberian for a total of 6.14 percent. I only score 0.39 percent Volga-Ural and nothing in the East Central Asian and Siberian elements.

Surviving autosomal DNA Identity by Descent (IBD)
       Inside GEDmatch, I found only two valid autosomal DNA segments of at least 7 centimorgans in length that are shared between this woman from Erfurt and modern Ashkenazim: the one I present below and one on chromosome 22 positioned from 34 million to 38 million. In general, the numbers of valid segments that each medieval Erfurt Jew shares with modern Jews are not large because only a small minority of their segments have remained unrecombined in the Jewish population to the present day. In some cases these segments' survival can probably be attributed to their location in more conserved regions of chromosomes or because of later parental ages in some lineages or because more fathers than mothers transmitted the segment up to the present day (less segments inherited from fathers get completely broken up and recombined by crossovers compared to those from mothers). Except for a few areas adjacent to Excess IBD Regions, the outer limit for survival of intact identical-by-descent segments with lengths of 6 or greater centimorgans is about 20 generations.
       I validated these segments by doing triangulation and parent-child phasing and by ensuring none of them are located in an Excess IBD Region. There is no way to determine whether any modern Ashkenazim directly descend from her or only are related to her through a common ancestor, such as one of her parents.

The following participants represent only a subset of the total matches I found to this segment:
EJ7716177: 14th-century Erfurt Jewish sample I14740
T788836: Janice M. Sellers = half-Ashkenazi Jewish + half European Christian; tested with Family Tree DNA
T781846: L. Z. G. = Ashkenazi Jewish; tested with Family Tree DNA
A698401: W. Metzger = 3/4th Ashkenazi + 1/4th non-Jewish Italian; tested with AncestryDNA
T577154: David Șloim Marcus = Ashkenazi Jewish; tested with Family Tree DNA
T731722: Shaun Marcus = Ashkenazi Jewish, son of David Șloim Marcus; tested with Family Tree DNA
M411264: Arnold Marcus = Ashkenazi Jewish, son of David Șloim Marcus; tested with 23andMe
M550241: Hillary D. = Ashkenazi Jewish, granddaughter of David Șloim Marcus' brother; tested with 23andMe
DS6892903: modern Polish Jew "Ashkenazi5788" from Iosif Lazaridis' 2014 data set; has relatively low SNP overlaps with the other kits due to chip incompatibilities

Their shared segment on chromosome 11 positioned from 18 million to 21 million:

Chromosome    Start Position    End Position    Centimorgans    SNPs

Comparing Kit EJ7716177 (Erfurt I14740) and Kit T788836 (Janice M. Sellers)
11                       18,950,092          21,425,793         7.6                      540

Comparing Kit EJ7716177 (Erfurt I14740) and Kit T781846 (L. Z. G.)
11                       18,787,044          21,425,793         7.8                      554

Comparing Kit EJ7716177 (Erfurt I14740) and Kit A698401 (W. Metzger)
11                       17,520,339          21,425,793         9.6                      630

Comparing Kit EJ7716177 (Erfurt I14740) and Kit T577154 (David Șloim Marcus)
11                       18,950,092          21,604,897         7.9                      576

Comparing Kit EJ7716177 (Erfurt I14740) and Kit T731722 (Shaun Marcus)
11                       18,950,092          21,425,793         7.6                      524

Comparing Kit EJ7716177 (Erfurt I14740) and Kit M411264 (Arnold Marcus)
11                       18,906,611          21,425,793         7.7                       749

Comparing Kit EJ7716177 (Erfurt I14740) and Kit M550241 (Hillary D.)
11                       18,973,545          21,425,793         7.6                       739

Comparing Kit EJ7716177 (Erfurt I14740) and Kit DS6892903 (Polish Jew Ashkenazi5788)
11                       18,278,098          21,183,993         8.1                       286

Triangulation
       Although triangulation technically refers to a minimum of 3 matches (the triangle), in my experience at least 4 matches are needed to be sure the matching isn't by chance. To confirm that a segment is valid, we always look to find at least four matches to a segment who are not close relatives and all of whom match each other in every possible combination with approximately the same start and end points across the same chromosome. It means that person A matches B, C, and D on the same segment, just as person B matches C and D and C matches D. In addition to that, it is beneficial to find that some close relatives share this segment. These processes help to weed out false matches.

Triangulations to establish this cluster of matches is identical-by-descent from a common ancestor:

Chromosome    Start Position    End Position    Centimorgans    SNPs

Comparing Kit T788836 (Janice M. Sellers) and Kit T781846 (L. Z. G.)
11                       18,796,480          22,803,712         10.3                    1,415
Comparing Kit T788836 (Janice M. Sellers) and Kit A698401 (W. Metzger)
11                       18,939,666          21,654,066         8                         797
Comparing Kit T788836 (Janice M. Sellers) and Kit T577154 (David Șloim Marcus)
11                       17,934,383          21,610,969         9.4                      1,326
Comparing Kit T788836 (Janice M. Sellers) and Kit T731722 (Shaun Marcus)
11                       17,934,383          21,654,066         9.5                      1,321
Comparing Kit T788836 (Janice M. Sellers) and Kit M411264 (Arnold Marcus)
11                       17,427,363          21,654,066         10.1                    1,497
Comparing Kit T788836 (Janice M. Sellers) and Kit M550241 (Hillary D.)
11                       16,829,568          23,374,739         13.8                    2,002
Comparing Kit T788836 (Janice M. Sellers) and Kit DS6892903 (Polish Jew Ashkenazi5788)
11                       18,973,545          22,786,413         10                       316

Comparing Kit T781846 (L. Z. G.) and Kit A698401 (W. Metzger)
11                       18,562,982          21,587,215         8.5                       841
Comparing Kit T781846 (L. Z. G.) and Kit T577154 (David Șloim Marcus)
11                       18,787,044          21,574,121         8.1                       1,111
Comparing Kit T781846 (L. Z. G.) and Kit T731722 (Shaun Marcus)
11                       18,762,983          21,587,215         8.2                       1,117
Comparing Kit T781846 (L. Z. G.) and Kit M411264 (Arnold Marcus)
11                       18,796,480          21,587,215         8.1                       1,064
Comparing Kit T781846 (L. Z. G.) and Kit M550241 (Hillary D.)
11                       18,195,348          22,395,192         10.5                     1,374
Comparing Kit T781846 (L. Z. G.) and Kit DS6892903 (Polish Jew Ashkenazi5788)
11                       18,795,058          21,537,221         8                          280

Comparing Kit A698401 (W. Metzger) and Kit T577154 (David Șloim Marcus)
11                       18,939,666          21,660,464         8                          796
Comparing Kit A698401 (W. Metzger) and Kit T731722 (Shaun Marcus)
11                       18,939,666          21,660,464         8                          781
Comparing Kit A698401 (W. Metzger) and Kit M411264 (Arnold Marcus)
11                       18,882,221          21,660,464         8.1                       813
Comparing Kit A698401 (W. Metzger) and Kit M550241 (Hillary D.)
11                       18,939,666          21,658,844         8                          802
Comparing Kit A698401 (W. Metzger) and Kit DS6892903 (Polish Jew Ashkenazi5788)
11                       18,278,098          21,983,447         9.6                       304

Comparing Kit T577154 (David Șloim Marcus) and Kit T731722 (Shaun Marcus)
11                       198,510               50,668,400         68.9                     13,152
Comparing Kit T577154 (David Șloim Marcus) and Kit M411264 (Arnold Marcus)
11                       198,510               50,668,400         68.9                     12,861
Comparing Kit T577154 (David Șloim Marcus) and Kit M550241 (Hillary D.)
11                       12,189,013          21,539,055         15.9                     2,705
Comparing Kit T577154 (David Șloim Marcus) and Kit DS6892903 (Polish Jew Ashkenazi5788)
11                       18,973,545          21,184,613         7.1                       229

Comparing Kit T731722 (Shaun Marcus) and Kit M411264 (Arnold Marcus)
11                       198,510               44,890,761         67                       11,976
Comparing Kit T731722 (Shaun Marcus) and Kit M550241 (Hillary D.)
11                       12,189,013          22,119,239         17                        2,810
Comparing Kit T731722 (Shaun Marcus) and Kit DS6892903 (Polish Jew Ashkenazi5788)
11                       18,973,545          21,184,613         7.1                       222

Comparing Kit M411264 (Arnold Marcus) and Kit M550241 (Hillary D.)
11                       12,189,013          22,030,566         16.8                     3,693
Comparing Kit M411264 (Arnold Marcus) and Kit DS6892903 (Polish Jew Ashkenazi5788)
11                       18,809,542          21,262,591         7.5                       325

Comparing Kit M550241 (Hillary D.) and Kit DS6892903 (Polish Jew Ashkenazi5788)
11                       18,973,545          21,262,591         7.3                       311

Future experimentation with the medieval Erfurt Jewish samples could involve attempting to match them to other medieval European Jews as well as to members of medieval European peoples to whom they were related within genealogically-significant timeframes such as Czechs, Germans, and Khazars. I already was able to find a 7.1 centimorgan segment match with 480 SNPs on chromosome 16 positioned from 18 million to 24 million between sample I14853 (GEDmatch SQ3204446), one of the Erfurt Jews, and sample SB676 (GEDmatch TU3514934), one of the Tzarfati (Northern French) Jews who were killed in Norwich, England in 1190, although this match has not been triangulated or phased. The Jews in Norwich were very genetically and culturally similar to the early and modern Jews from Rhineland Germany.

Postscript
       UNESCO names Erfurt's medieval Jewish buildings in Germany as a World Heritage Site.
       Erfurt's Jews who were buried in the cemetery and supplied the DNA samples weren't representatives of Erfurt's original Jewish community that had built the Old Synagogue in the 11th-14th centuries and attended it until the Erfurt massacre and expulsion of 1349, but rather those who moved in from other towns a few years later.

Acknowledgements
All of the aforementioned living, non-anonymous GEDmatch participants gave me written permission to have their kits represented in this article and they saw drafts of this article before I submitted it. Thanks to the Erfurt study's co-author Shai Carmi of the Hebrew University of Jerusalem for his feedback on this and similar Erfurt DNA segments. Thanks also to the Erfurt study's co-author Leo Cooper for feedback on a draft of this article.

Bibliography:

      Jim Bartlett, Segmentology.org
      Selina Brace, Yoan Diekmann, Thomas Booth, Ruairidh Macleod, Adrian Timpson, Will Stephen, Giles Emery, Sophie Cabot, Mark G. Thomas, and Ian Barnes, "Genomes from a medieval mass burial show Ashkenazi-associated hereditary diseases pre-date the 12th century," Current Biology, October 24, 2022, pages 4350-4359.e6 plus supplements.
      Mansha Jia, Qiuyan Li, Tingting Zhang, Bonan Dong, Xiao Liang, Songbin Fu, and Jingcui Yu, "Genetic Diversity Analysis of the Chinese Daur Ethnic Group in Heilongjiang Province by Complete Mitochondrial Genome Sequencing," Frontiers in Genetics, June 21, 2022, article no. 919063 plus supplements.
      Péter L. Nagy, Judit Olasz, Endre Neparáczki, Nicholas Rouse, Karan Kapuria, Samantha Cano, Huijie Chen, Julie Di Cristofaro, Goran Runfeldt, Natalia Ekomasova, Zoltán Maróti, János Jeney, Sergey Litvinov, Murat Dzhaubermezov, Lilya Gabidullina, Zoltán Szentirmay, Gyórgy Szabados, Dragana Zgonjanin, Jacques Chiaroni, Doron M. Behar, Elza Khusnutdinova, Peter A. Underhill, and Miklós Kásler, "Determination of the phylogenetic origins of the Árpád Dynasty based on Y chromosome sequencing of Béla the Third," European Journal of Human Genetics, January 2021, pages 164-172 plus supplements.
      Shamam Waldman, Daniel Backenroth, Éadaoin Harney, Stefan Flohr, Nadia C. Neff, Gina M. Buckley, Hila Fridman, Ali Akbari, Nadin Rohland, Swapan Mallick, Iñigo Olalde, Leo Cooper, Ariel Lomes, Joshua Lipson, Jorge Cano Nistal, Jin Yu, Nir Barzilai, Inga Peter, Gil Atzmon, Harry Ostrer, Todd Lencz, Yosef E. Maruvka, Maike Lämmerhirt, Alexander Beider, Leonard V. Rutgers, Virginie Renson, Keith M. Prufer, Stephan Schiffels, Harald Ringbauer, Karin Sczech, Shai Carmi, and David Reich, "Genome-wide data from medieval German Jews show that the Ashkenazi founder event pre-dated the 14th century," Cell, December 8, 2022, pages 4703-4716.e16 plus supplements.

Kevin Alan Brook is a historian and population geneticist whose most recent book is The Maternal Genetic Lineages of Ashkenazic Jews.

      An article of related interest which links to the article above: "DNA says you’re related to a Viking, a medieval German Jew or a 1700s enslaved African? What a genetic match really means" by Shai Carmi and Harald Ringbauer in The Conversation, March 29, 2024.

Disclosure: Compensated affiliate of genetic testing companies, bookstores, and Nature.com