Explain why historians do not have an exact date for the ending of the chou dynasty?

There is no exact date for the ending of Chou Dynasty because the nobles wanted it to end slowly enough for them to retain their power structure.

Assemblies do not have written codes of laws. laws are matters for magistrates and courts, not assemblies. codes of law are things such as civil law, criminal law, and constitutional law. what assemblies have are procedures regarding debating, voting and other business they might carry out.  also note that rome had three assemblies: the assembly of the soldiers, the assembly of the tribes, and the plebeian councils.

Your gonna need to tell me more