For the same reason people chew gum today - to relieve hunger and thirst and to freshen breathe. They also relied on chewing gum for routine dental hygiene. The Gabrielino people of Southern California boiled milkweed sap and chewed the result for gum. Other Native Americans used several substances for chewing gum, such as licorice and marshmallow roots, sweet gum, and hollyhock. Native Americans taught New England colonists to chew spruce sap as a breathe sweetener. The practice quickly became a fad. Spruce gum was being sold by the lump in Eastern United States by the early 1800's making it the first commercial chewing gum.