The Afghan Turkmen population in the 1990s was estimated at around 200,000. The original Turkmen groups came from east of the Caspian Sea into northwestern Afghanistan at various periods, particularly after the end of the 19th century when the Russians moved into their territory. They established settlements from Balkh Province to Herat Province, where they are now concentrated; smaller groups settled in Kunduz Province. Others came in considerable numbers as a result of the failure of the Basmachi revolts against the Bolsheviks in the 1920s. Turkmen tribes, of which there are twelve major groups in Afghanistan, base their structure on genealogies traced through the male line. Senior members wield considerable authority. Formerly a nomadic and warlike people feared for their lightning raids on caravans, Turkmen in Afghanistan are farmer-herdsmen and important contributors to the economy. They brought karakul sheep to Afghanistan and are also renowned makers of carpets, which, with karakul pelts, are major hard currency export commodities. Turkmen jewelry is also highly prized.