China's Treasury holdings dwarf all but a few nations, and it's by far the largest holder, excluding Japan which tails only slightly. "Carribean Banking Centers", oil exporters, and Brazil follow, the last with only just over a quarter of China's holdings. Few emerging countries have any significant holdings.
Of course, major foreign holders only hold a third of the total Treasuries. US Government agencies actually own another third of the debt, and the US public owns the last third.