Complex sentence: A Genetic History of the Jewish People, which summarized his and other work in genetics of the last 20 years concluded that all major Jewish groups had common Middle Eastern origin and refuted any large-scale genetic contribution from the Turkic Khazars.
Split into simpler sentences: A Genetic History of the Jewish People, which summarized his and other work in genetics of the last 20 years. The studies he cites have refuted any large-scale genetic contribution from the Turkic Khazars.