Mainland China was known as Red China, and the Taiwan Government was considered the legitimate government of China. I think Carter also placed the Chinese in control of the Panama Canal at that time - a negative for our national security.
He took a democratic government and force them to give up their Security Council seat to a communist regime. He did give away the Panama Canal but China took it over later. The great William F Buckley debated Ronal Reagan on the Canal giveaway. Reagan made a great showing but they gave it away anyway.
Of course one has to remember that Nixon was the one that opened China to the free world.