In 2013, however, a study of Ashkenazi mitochondrial DNA by a team led by Martin B. Richards of the University of Huddersfield in England reached different conclusions, again corroborating the pre-2006 origin hypothesis. Testing was performed on the full 16,600 DNA units composing mitochondrial DNA (the 2006 Behar study had only tested 1,000 units) in all their subjects, and the study found that the four main female Ashkenazi founders had descent lines that were established in Europe 10,000 to 20,000 years in the past while most of the remaining minor founders also have a deep European ancestry. The study states that the great majority of Ashkenazi maternal lineages were not brought from the Near East (i.e., they were non-Israelite), nor were they recruited in the Caucasus (i.e., they were non-Khazar), but instead they were assimilated within Europe, primarily of Italian and Old French origins. Richards summarized the findings on the female line as such: "[N]one [of the mtDNA] came from the North Caucasus, located along the border between Europe and Asia between the Black and Caspian seas. All of our presently available studies including my own, should thoroughly debunk one of the most questionable, but still tenacious, hypotheses: that most Ashkenazi Jews can trace their roots to the mysterious Khazar Kingdom that flourished during the ninth century in the region between the Byzantine Empire and the Persian Empire." The 2013 study estimated that 80 percent of Ashkenazi maternal ancestry comes from women indigenous to Europe, and only 8 percent from the Near East, while the origin of the remainder is undetermined. According to the study these findings "point to a significant role for the conversion of women in the formation of Ashkenazi communities."