A stonemason named Bartholomew of Sandwich led a group of his followers to New York from England, having seen the Underland in a dream. Because he believed that the Earth, above ground, would one day be empty of life, he ordered the building of a city underground. After 50 years of preparation, Sandwich and 800 others went beneath and sealed all but five gates to the Overland.
In order for humans to be able to inhabit the Underland, Sandwich needed to have land for them on which to live. The land Sandwich chose was inhabited by the diggers (giant star-nosed moles), who refused to give up their land without a fight. Sandwich realized he could not beat the diggers without sustaining heavy losses himself; therefore he poisoned their water supply, thought to be killing all of them. This land became the site of Regalia.