Soviets did use M39- and M42-screwmounts very early, and then Nikon-bayonet (Kiev) & Pentax-K (Zenit, Almaz), plus some own shorter lived ones (Zenit and Kiev). So there was no need for Minolta-bayonet, like in China, which didn't have the history of using screwmount widely. And BTW even Chinese took Pentax-K as their main mount later. http://sivut.ws/cedricfan/website/My%20cameras/Chinese%20SLR/index.html
Thanks for that link. You are correct that the Chinese used the Pentax K mount on many of their cameras. They also made many 35mm SLR cameras with Nikon, Contax/Yashica, and M42 (Universal/Praktica) mounts. But by far most Chinese 35mm SLR cameras (typically, Seagull) used the Minolta SR mount -- some slightly modified, such as the Pearl River.