Several macrofamily schemes have been proposed for linking multiple language families of Southeast Asia. None of these proposals have been accepted by mainstream comparative linguistics, though research into higher-level relationships among these languages has gained some renewed scholarly interest over the last three decades; the various hypotheses are still under investigation, and the validity of each has yet to be resolved.[2]
Austro-Tai links the Austronesian and Kra–Dai languages. Several linguists, including Laurent Sagart, Stanley Starosta, Weera Ostapirat and Lawrence Reid,[3] accept or theorize a close relationship between these families, but the specifics of the relationship remain unclear. Multiple models of the internal branching of Austro-Tai have been put forward, and Austro-Tai has been incorporated as a subgroup within some larger macrofamily schemes, e.g. in Starosta's East Asian as well as in Sagart's model of Austronesian (see below), both of which regard Kra–Dai as a subfamily within Austronesian. A few versions of Austro-Tai have included Japonic and/or the isolate Ainu as well, though these have not been met with as much acceptance.
Miao–Dai (Kosaka 2002) is a hypothesis for a family including Miao–Yao (Hmong–Mien) and Kra–Dai.[4]
Sino-Austronesian (Sagart 2004, 2005) links Austro-Tai (Austronesian) with Sino-Tibetan (Tibeto-Burman).
Austric links all of the major language families of Southeast Asia apart from Sino-Tibetan. Several variants of the Austric hypothesis have been proposed since it took shape with Paul K. Benedict's proposal (1942). Some of these also incorporate Japonic, Korean and/or Ainu. One version called the "Greater Austric" hypothesis (Bengtson 1996) includes Ainu as well as Nihali, a language isolate of India.[5]
The "Proto-Asian hypothesis" or "Austro-Asian" (Larish 2006) argues for lexical evidence of relationship among all of the languages typically included in Austric as well as Japanese–Korean and Sino-Tibetan.[6]
East Asian (Starosta 2005) covers all of these families (except Japonic, Koreanic, Ainu and Nihali) as well as Sino-Tibetan. It posits Austronesian (including Kra–Dai) as the most divergent branch, coordinate with a primary branch Sino-Tibetan–Yangzian which links Sino-Tibetan with a clade called Yangzian (or Yangtzean), named for the Yangtze river, which includes Austroasiatic and Hmong–Mien.
Genetic similarities between the peoples of East and Southeast Asia have led some scholars such as George van Driem to speculate about "Haplogroup O languages".
Reid, Lawrence A. (2006). "Austro-Tai Hypotheses". pp.609–610 in Keith Brown (editor in chief), The Encyclopedia of Language and Linguistics, 2nd edition.
Blust, Robert A. 2009. The Austronesian Languages. Canberra: Pacific Linguistics, Research School of Pacific and Asian Studies, Australian National University. ISBN0-85883-602-5, ISBN978-0-85883-602-0.
Matisoff, James. 2003. Handbook of Proto-Tibeto-Burman: System and Philosophy of Sino-Tibetan Reconstruction. University of California publications in linguistics, v. 135. Berkeley: University of California Press.