This basically happened because of survival tactics that the tortoise had to get. This is in terms of shelter end even what your pet ate as well as keeping away from predators. You can consult with your vet to examine the tortoise and be sure that he is fine
Russian tortoises are wild animals that managed to survive for thousands of years without interference from people. If he found adequate water and a reasonable temperate climate he would have no problem surviving. Russian tortoises eat fruits, vegetables and grasses. I'm guessing those are not too hard to find in your neighborhood. It can go for long periods without eating as well.