When it comes to the Indian Ocean System in the thirteenth century, it was divided into three parts. The Arabian Sea, the Indian Ocean, and the South China Sea were all divided, yet they all worked together. Each part was influenced by one or more different cultures. These divisions were not necessarily strictly political, but more or less geographical.
In the westernmost part of this division, the Muslims were the dominant ones. The Muslims were from the Arabian Peninsula and the capitals of Baghdad and Cairo.
In the middle, Abu-Lugbod says this area was "primarily 'hinduized' in culture." The middle connected the south Indian coast. The cities were Malabar in the west and Coromandel in the east with everything else in between, and a few islands of Indonesia. She also points out that there were several Buddhist and Chinese influences.
And in the east of course we have China. According to the map, this division was the biggest. This area was dominated by Buddhists and Confucianism.
Her point in discussing all of these great cultures of this divided trade route system is not to prove whose culture was the most dominant, but to prove how these cultures could trade freely "within each of the three zones". The different cultures didn't set the boundaries between these divisions, rather it was the geographical attributes and the weather that divided these areas and cultures. It was the where the "countercyclical wind patterns met" that separated the monsoon areas and divided these trade areas. "...the 'natural' condition of the Indian Ocean was for several locally hegemonic powers to coexist; no single power ever exercised dominance over the entire system (253)."