Table 2:

Fitting proxies for the new ancestry source in Iron Age southern Britain

Proxies for source of the new ancestry	N	Mean date	p-value	Ancestry
Margetts Pit and Cliffs End Farm M-LBA	4	1036 BCE	0.07	49.4 ± 3.0%
Spain IA Tartessian	2	629 BCE	0.16	23.7 ± 1.2%
France GrandEst IA1 (shotgun data)	5	620 BCE	1.00	48.9 ± 3.7%
France Occitanie IA2 (high EEF subgroup, shotgun data)	1	450 BCE	0.85	25.8 ± 1.7%
France Occitanie IA2 (high WHG subgroup, shotgun data)	1	450 BCE	0.39	33.5 ± 4.1%
France Occitanie IA2 (shotgun data)	2	400 BCE	0.25	53.3 ± 5.4%
France Occitanie IA2 (low Steppe subgroup, shotgun data)	2	363 BCE	0.33	36.5 ± 2.6%
France GrandEst IA2	12	250 BCE	0.09	68.5 ± 3.3%

Note: We fit the pooled IA individuals from England and Wales as a mixture of the pooled C/EBA individuals from England and Wales and a proxy for the new ancestry source. The p-value is from qpAdm’s test of fit of each population as a two-way admixture with no correction for multiple hypothesis testing. These results represent eight of the 65 lines in Supplementary Information section 6, Table S6.1