The gospels tell us that on one occasion Jesus exorcised a man of demons who called themselves "Legion" because there was about..."two thousand of them." These demons are cast by Jesus into a large herd of pigs, which rush over the edge of a hillside and are drowned.
Exactly the motif is found in the rites of the Mysteries at Eluesis ( about 20-40 miles from Greece) As part of the purification ceremony before initiation, some 2 thousand initiates all bathed in the sea with young pigs. This bathing ritual banished all evil into the pigs, which were then sacraficed, as a symbol of the initiates own impurities, by being chased over a chasm.
These latter rites and performances were LONG before Jesus time. Pigs were used in MANY rites as such by others, if you'll take the time to check it out.
For refrences a person can simply type in 'Eleusis' in a serch engine and read a bit on it.
Or...... See Burkert, W.(1985), or Harrison,J.(1922) 153 Harrison, op cit., 152 Burkert, op.cit, 242
Gumby