He wasn't summoned in more than one thousand years. He wasn't like any other demon trade. A demon trade was a middle-high tier demon that like his name says he can make a "trade" with the humans. It can be summoned only once and the humans can trade their soul, which is the most sought out trade for this type of demons. Is not the case every time, depends on the wish or difficulty. You can trade from spiritual plants and magic artifacts to humans souls. But a demon trade cannot appear by himself. He can only be summoned by a human and that requires the use of a spell, and those spells were not that easy to do and requires some items too. Requesting a wish from a demon was not as simple as it sounds. Demon trade were tricky creatures, he'll give you what you want but it might not be what you need. Also, a demon trade can't stay in the human world for too long, he only has two days limit to the make the trade.
