Celts, Germans, Latins and Slavs all speak Indo-European who are believed to have come from the East. Ancient peoples who first settled Europe probably spoke something akin to Basque. Europeans are a hybrid race. Why they chose Indo-European languages over their ancient tongues remains a mystery.
"The Tocharians were the easternmost speakers of an Indo-European language in antiquity, inhabiting the Tarim basin in what is now Xinjiang Uyghur Autonomous Region, northwestern People's Republic of China. "