be closely related to Khmuic. If this would the case, Sidwell & Blench suggest that Khasic may have been an early offshoot of Palaungic that had spread westward. Sidwell & Blench (2011) suggest Shompen as an additional branch, and believe that a Vieto-Katuic connection is worth investigating. In general, however, the family is thought to have diversified too quickly for a deeply nested structure to have developed, since Proto-Austroasiatic speakers are believed by Sidwell to have radiated out from the central Mekong river valley relatively quickly. Subsequently, Sidwell (2015a: 179) proposed that Nicobarese subgroups with Aslian, just as how Khasian and Palaungic subgroup with each other. A subsequent computational phylogenetic analysis (Sidwell 2015b) suggests that Austroasiatic branches may have a loosely nested structure rather than a completely rake-like structure, with an east–west division (consisting of Munda, Khasic, Palaungic, and Khmuic forming a western group as opposed to all of the other branches) occurring possibly as early as 7,000 years before present. However, he still considers the subbranching dubious. Integrating computational phylogenetic linguistics with recent archaeological findings, Paul Sidwell (2015c) further expanded his Mekong riverine hypothesis by proposing that Austroasiatic had ultimately expanded into Indochina from the Lingnan area of southern China, with the subsequent Mekong riverine dispersal taking place after the initial arrival of Neolithic farmers from southern China. Sidwell (2015c) tentatively suggests that Austroasiatic may have begun to split up 5,000 years B.P. during the Neolithic transition era of mainland Southeast Asia, with all the major branches of Austroasiatic formed by 4,000 B.P. Austroasiatic would have had two possible dispersal routes from the western periphery of the Pearl River watershed of Lingnan, which would have been either a coastal route down the coast of Vietnam, or downstream through the Mekong River via Yunnan. Both the reconstructed lexicon of Proto-Austroasiatic and the archaeological record clearly show that early Austroasiatic speakers around 4,000 B.P. cultivated rice and millet, kept livestock such as dogs, pigs, and chickens, and thrived mostly in estuarine rather than coastal environments. At 4,500 B.P., this "Neolithic package" suddenly arrived in Indochina from the Lingnan area without cereal grains and displaced the earlier pre-Neolithic hunter-gatherer cultures, with grain husks found in northern Indochina by 4,100 B.P. and in southern Indochina by 3,800 B.P. However, Sidwell (2015c) found that iron is not reconstructable in Proto-Austroasiatic, since each Austroasiatic branch has different terms for iron that had been borrowed relatively