▁continu um ▁with ▁Northern ▁Tai ▁vari eties ▁across ▁the ▁provincial ▁border ▁in ▁Gu iz hou , ▁which ▁are ▁designated ▁as ▁Bou ye i , ▁whereas ▁Southern ▁Z hu ang ▁languages ▁form ▁another ▁dialect ▁continu um ▁with ▁Central ▁Tai ▁vari eties ▁such ▁as ▁N ung , ▁T ay ▁and ▁Ca olan ▁in ▁Vietnam . ▁Standard ▁Z hu ang ▁is ▁based ▁on ▁the ▁Northern ▁Z hu ang ▁dialect ▁of ▁W uming . ▁ ▁The ▁Tai ▁languages ▁are ▁believed ▁to ▁have ▁been ▁originally ▁spoken ▁in ▁what ▁is ▁now ▁southern ▁China , ▁with ▁speak ers ▁of ▁the ▁South western ▁Tai ▁languages ▁( which ▁include ▁Th ai , ▁La o ▁and ▁Sh an ) ▁having ▁em igr ated ▁in ▁the ▁face ▁of ▁Chinese ▁expansion . ▁Not ing ▁that ▁both ▁the ▁Z hu ang ▁and ▁Th ai ▁pe op les ▁have ▁the ▁same ▁ex onym ▁for ▁the ▁Vietnam ese , ▁k ɛ ɛ u A 1 , ▁from ▁the ▁Chinese ▁command ery ▁of ▁J ia oz hi ▁in ▁northern ▁Vietnam , ▁Jer old ▁A . ▁Ed mond son ▁pos ited ▁that ▁the ▁split ▁between ▁Z hu ang ▁and ▁the ▁South western ▁Tai ▁languages ▁happened ▁no ▁earlier ▁than ▁the ▁found ing ▁of ▁J ia oz hi ▁in ▁ 1 1 2 ▁BC . ▁He ▁also ▁arg ues ▁that ▁the ▁departure ▁of ▁the ▁Th ai ▁from ▁southern ▁China ▁must ▁pre date ▁the ▁ 5 th ▁century ▁AD , ▁when ▁the ▁Tai ▁who ▁remained ▁in ▁China ▁began ▁to ▁take ▁family ▁names . ▁ ▁Sur ve ys ▁ ▁Zh ā ng ▁J ū