World Language Families
Indo-European is the language family with the largest number of native speakers in the world, spoken today by well over three billion people across a territory that stretches, historically, from South Asia to Western Europe, and that has expanded through colonization to the Americas, Australia, and parts of Africa. Its major branches include Germanic (English, German, Dutch, and the Scandinavian languages), Romance (Spanish, Portuguese, French, Italian, and Romanian, all descended from Latin), Slavic (Russian, Polish, Ukrainian, and Serbian, among others), Indo-Iranian (Hindi-Urdu, Bengali, Persian, and Punjabi), and smaller branches such as Celtic (Irish, Welsh, and Scottish Gaelic, now minority languages), Hellenic (Greek), Baltic (Lithuanian and Latvian), Armenian, and Albanian. The geographic reach of this single family illustrates how deeply migration, conquest, and colonization have reshaped the linguistic map of the planet.
Why do you think there's historiographical debate about "World Language Families"?