Yes, merchants. My recent game had puppets spawn 7 merchants. They were running no specialists and all wonder cities had been annexed.
Incidentally, a customs house goes on top of a TP or plantation. For example, a CH on a plantation is +6 gpt. If it is riverside in a commerce (SP) capitol during a GA with a stock exchange it becomes > 16 gpt. Also, manufactories go on top of mines.