So, right, you wouldn't let an army or a rival noble into your house, but everyone welcomes a merchant, and not just royalty. The great thing about seaborne trade is that you can trade bulk goods, like cotton cloth, foodstuffs, and timber that's all too heavy to strap onto a camel or mule. So for the first time we see goods being traded for a mass market instead of just luxury goods like silk for elites. Wood, for instance, can be used to build houses, but it's not all that plentiful on the Arabian Peninsula. However, when it becomes cheaper, thanks to trade, suddenly more people can have better houses. Much of the timber that was shipped in the monsoon marketplace came from Africa, which was kind of emblematic. Africa produced a lot of the raw materials, like animal hides and skin and ivory and gold.