A large wall surrounds Otogakure, not of physical material, well not exactly. The wall is identified by large metal poles circling the village every mile. The newly built rode leading to Otogakure is protected by a large outpost, heavily guarded. The only way to get in without going through the outpost or flying more than 10 miles above the ground to get over the sound barrier is a secret sheep herders trail that leads through what looks to be a large mountain at the back of the village, but is really just an illusion. The Otokage takes this road when he travels.