I would not jump to the conclusion solely based on isotope signatures. A decade or so ago, a prominent Chinese professor Weidong Sun specialized in geochemistry analyzed the ancient bronze artifacts dated back to the Shang dynasty and found isotope signatures pointing to a Mediterranean origin, and he had to answer that. Well there can be several explanations, for example, the Shang people traded with central Asian tribes and got the ores and perhaps the bronze smelting tech too. But Sun, based on some ancient documents on some mythical long travel of the ancestors of the Shang people, concluded that the only reasonable explanation is that the Shang people are offsprings of those tribes, who are offsprings of the Sumerian people.
