This historian didn't know chams are malays but were driven out by the vietnamese and Thais. The malays were, like everyone else in south east asia, influenced by dravidian tamils.
The sailing experience and know how probably from tamils, as they sailed from india all the way yo korea. How else you think budhism can spread so far.
But the linking of cham culture to that of south america is not proven. Intially it was said to be polynesian from taiwanese aborigines. But taiwanese otang asli have no mortar like buildings.umless the ones they found at the botttom of the ocean can be counted as one. There is also another similar underwater structure in japan.
