Indo-European, as everybody should know, is the language family encompassing all languages from Western Europe to Iran and India. This is the beginners explanation of the centum-satem west-east split of these languages: The Tocharian languages' word for 100 belongs to the "centum" (Latin centum, English hundred are descendent words in this group), along with the Germanic, Celtic, Italic and other western branches of the Indo-European language family, as opposed to the more eastern group of the Indian, Iranian, and Slavic group of languages whose word for 100 is derived from "satem", no nasalized vowel or hardened initial consonant. But why is the "centum" language Tocharian only found on items from the Tarim Basin, thousands of miles from the other "centum" groups like Italic and Germanic? Supposedly the development of the "satem" language features arose in the eastern part of the Indo-European homeland after the emigration of the group now known as Tocharian.
The Tocharian people lived 2000BC into the first millenium CE, until the Uighurs overran the Tarim Basin in 800AD or something like that, but the people of the area still have features like red hair and blue eyes, so ponder that.
That is the 30000 foot overview of the Tocharians, the name is cool but is probably an inaccurate exonym.
Geologically, the basin is a micro-continent embedded in the Asian supercontinent, once a separate land mass but now quite ensconced within Asia, ringed with its mountains. It's a forsaken desert surrounded by mountain stream nurtured oasis Silk Road towns for 4000 years now