Shackles
The man was in horrible shape when Jesus met up with him. He terrorized the region he lived in. The towns people didn't know what to do with him so they tried chains and shackles. When that didn't work, they just put him out in the tombs.
Who could blame them? A "legion" was thousands of soldiers. Even if the demon was bragging when he called himself Legion, that is a lot of demons. This man created some major havoc. The region of Gerasenes was fairly sophisticated, and this guy was really causing trouble. Most tourism brochures are not filled with "Come see our demon possessed man." All they wanted was life to be back to normal so that their region would be safe again.
But one thing we learn from this story is that transformation does not come from binding.
We may have good intentions, but in the end, nothing happens. It may look good for a while, but no transformation takes place.
The solution is much more simple, but that doesn't make it easy.