It was Iran. Plus the U.S. and Kazakhstan.
Actually most of them moved to Kazakhstan. Iran had a nice hash rate before the China ban. In fact during Trump era Iran included bitcoin in their annual budget to be used for imports/exports too but everything about Iran's international trades is kept under wraps (unless it is with another sanctioned nation or China) so we don't really know the real values.
By my estimates according to some reports of energy consumption and the taxes, I believe Iran currently has a little less than 20% of the total hashrate and that is growing fast.
Keep in mind that electricity in Iran has always been dirt cheap (0.002 $/KWH), a lot less than China.
I believe if the potential advantages for HODLing Bitcoin is truly understood by these countries with “dirt cheap” electricity, the government themselves would be setting up their own mining farms. The advantages will be understood, after realization that the inflation seen all around is irreversible.