▁ 1 9 9 7 ; ▁Z hang ▁ 1 9 9 9 : 2 9 - 3 0 ). ▁The ▁W uming ▁dialect ▁of ▁Y ong bei ▁Z hu ang , ▁class ified ▁within ▁the ▁" N or thern ▁Z hu ang ▁dialect ," ▁is ▁considered ▁to ▁be ▁the ▁" standard " ▁or ▁prest ige ▁dialect ▁of ▁Z hu ang , ▁developed ▁by ▁the ▁government ▁for ▁certain ▁official ▁us ages . ▁Although ▁Southern ▁Z hu ang ▁vari eties ▁have ▁asp ir ated ▁stops , ▁Northern ▁Z hu ang ▁vari eties ▁lack ▁them . ▁There ▁are ▁over ▁ 6 0 ▁distinct ▁t onal ▁systems ▁with ▁ 5 – 1 1 ▁t ones ▁depending ▁on ▁the ▁variety . ▁ ▁Z hang ▁( 1 9 9 9 ) ▁identified ▁ 1 3 ▁Z hu ang ▁vari eties . ▁Later ▁research ▁by ▁the ▁Summer ▁Institute ▁of ▁L ingu istics ▁has ▁indicated ▁that ▁some ▁of ▁these ▁are ▁themselves ▁multiple ▁languages ▁that ▁are ▁not ▁mut ually ▁intellig ible ▁without ▁previous ▁expos ure ▁on ▁the ▁part ▁of ▁speak ers , ▁resulting ▁in ▁ 1 6 ▁separate ▁ISO ▁ 6 3 9 - 3 ▁codes . ▁ ▁Northern ▁Z hu ang ▁ ▁Northern ▁Z hu ang ▁compr ises ▁dialect s ▁north ▁of ▁the ▁Y ong ▁River , ▁with ▁ 8 , 5 7 2 , 2 0 0 ▁speak ers ▁( ▁prior ▁to ▁ 2 0 0 7 ): ▁ ▁Gu ib ei ▁ <0xE6> <0xA1> <0x82> 北 ▁( 1 , 2 9 0 , 0 0 0 ▁speak ers