At first, historical linguistics served as the cornerstone of comparative linguistics, primarily as a tool for linguistic reconstruction. Scholars were concerned chiefly with establishing language families and reconstructing unrecorded proto-languages, using the comparative method and internal reconstruction. The focus was initially on the well-known Indo-European languages, many of which had long written histories; scholars also studied the Uralic languages, another Eurasian language-family for which less early written material exists. Since then, there has been significant comparative linguistic work expanding outside of European languages as well, such as on the Austronesian languages and on various families of Native American languages, among many others. Comparative linguistics became only a part of a more broadly-conceived discipline of historical linguistics. For the Indo-European languages, comparative study is now a highly specialized field. Most research is being carried out on the subsequent development of these languages, in particular, the development of the modern standard varieties.