What economic gains did Alexander the Great obtain from conquering territories? He acquired a system of taxation.
He obtained new forms of technology.
He developed new trading partners.
He no longer relied on the spice trade.

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.