Definitions for wagon train
Random House Webster's College Dictionary
a train of wagons and horses, as one transporting settlers in the westward migration.
Origin of wagon train:
caravan, train, wagon train(noun)
a procession (of wagons or mules or camels) traveling together in single file
"we were part of a caravan of almost a thousand camels"; "they joined the wagon train for safety"
A number of horse-drawn wagons traveling together for safety.