Horde
noun
A wandering troop or gang; especially, a clan or tribe of a nomadic people (originally Tatars) migrating from place to place for the sake of pasturage, plunder, etc.; a predatory multitude.
A large number of people.
“We were beset by a horde of street vendors who thought we were tourists and would buy their cheap souvenirs.”
verb
To travel en masse, to flock