Complex sentence: There is a major difference of Zhai's theory with the above-mentioned models: he proposed that the North China Craton, instead of simply amalgamated and formed from the Eastern and Western Blocks, was amalgamated from a total of 7 ancient blocks.
Split into simpler sentences: There is a major difference of his theory with the above-mentioned models though. He proposed that the North China Craton, instead of just simply amalgamated from the Eastern and Western Blocks, it was amalgamated from 7 ancient blocks.