1) We have learned that the celts are the ones traced back to the beginning of Halloween (2000 years ago).
2) The celts celebrated this day because it marked the end of summer and harvest the beginning of a dark long and cold winter, the time of year that was often associated with human death.
3) The celts believed that the ghosts of the dead returned to earth.
4) example #1 they built Huge sacred bonfires, #2 they sacrificed animals and crops to the Celtic deities, 3# they wore costumes typically consisting of animal heads and skins and attempted to tell each other's fortune.
5) The Roman Empire had conquered the majority of the Celtic territory.
6) The religion of christianity had spread into the Celtic lands where it had started to blend in with supplanted the older Celtic rites.
7) The church made it this day to honor the dead at peace.
8) It is widely believed today that the church was attempting to replace the Celtic festival of the dead with a related church-sanctioned holiday.
9) The all saints day was also called (All-hallows) and (All-hallowmas)
10) I cannot see #10 but if you would like comment it under this and I'd be glad to answer it thanks!