However during the ESTATES GENERAL the 3RD ESTATE with some help from other PEOPLE declared a new government which they called the NATIONAL ASSEMBLY.

I changed Estates to people. Does the rest of this make sense?

Yes. It makes sense.

thank you.

Yes, the rest of the sentence still makes sense. By changing "Estates" to "people," the sentence indicates that the Third Estate, along with some assistance from other individuals, declared a new government called the National Assembly during the Estates General. The main idea is still conveyed effectively.