What are internal and external economies of scale? How do you explain these concepts using China's One Belt One Road initiative and the establishment of special economic zones?

Please explain why the semi-conductor industry is concentrated in California (Silicon Valley); Investment banking in New York; entertainment in Hollywood; Manufactured products exporters in Guangzhou (Guangdong), and Software (information services) in Bangalore.

How does a monopolistic market structure responds to international trade? Start your analysis from autarky.