In the beginning...
Most US "warehouses" used by Chinese suppliers were actual, real (I won't say legitimate), 3PL facilities; almost exclusively owned, operated, and staffed by fellow Chinese.
At some point some suppliers began transitioning to using private individuals who likely started out as customers or were domestic vendors as "warehouses", but unlike the 3PL model where they might have one to three warehouses, they started to engage several people and spread the inventory out so no single "warehouse" had more inventory than they were willing to lose if the person ripped them off. This is the main reason so many suppliers have a harder time keeping track of inventory and have delays or end up shipping from China because these people playing warehouse in their garage or spare bedroom are at best using email and spreadsheets instead of a WMS (warehouse management system) to keep track of things.
