As forex trading is divided into four major sessions, that is Sydney, Tokyo, London and New York. We can get highest market flows in this zones. But you will get to see highest market flow at London Session. Because it is the busiest session of all.
Having the different market session does not necessary means that at a certain session that basically, traders are often from that said country. Because the usd has more value and also is a currency been used in the New york city. Traders who invariably have it as their based currency will prefer trading it at the new york time session and are traders from different countries.