请问：这里的what 指代什么？

At the same time of the Mexican ograrian revolution, the most radical faction, that of Zapata and his followers, proposed a return to communal ownership of land, to what had been a pre-Columbian form of ownership respected by the Spaniards.

请问：What指代什么？这句话怎么译？

多谢！

At the same time of the Mexican ograrian revolution, the most radical faction, that of Zapata and his followers, proposed a return to communal ownership of land, to what had been a pre-Columbian form of ownership respected by the Spaniards.

很奇怪， what从句是communal ownership of land的同位语，却将前面的 to 也补了出来，我想应该是为了明确表示：what 是ownership的同位语，如果不加to,那么what 会被认为是land的同位语

电脑坏了，好多天没上来。

我明白了。谢谢大家阿！