Before the European invasion, the land now known as Montgomery County was covered in a vast swath of forest. The land was crossed by small streams and creeks that feed the Patuxent and Potomac rivers. A few small villages of the Piscataway were scattered across the southern parts of Montgomery County. In the northern portions of the county, there were a few permanent settlements, and Piscataway shared footpaths and hunting camps with members of rival groups like the Senecas and Susquehannocks.
The earliest settlers of Montgomery County were Scottish or English immigrants from other areas of Maryland. There were also German settlers moving down from the state of Pennsylvania. Some Christian missionaries moving from the west were also part of the early settlers of this county. Most of the early settlers were small farmers who grew wheat and various other crops. Tobacco was the region's primary cash crop, with many farmers in Montgomery planting it. In the late 1770s, there was a growing movement to form a new strong federal government in Maryland. The proposal was to give each colony in Maryland (now called counties) the authority to govern their local affairs.
On August 31, 1776, a plan was proposed to form a new county government from the southern portion of the then Frederick County. This proposal saw the creation of Montgomery County, which came into existence on October 1, 1776. Since its establishment, Montgomery has grown significantly, ranking among the wealthiest counties in the United States in recent years. The ever-increasing economy in the region makes houses for sale in Montgomery County, Maryland, highly valuable.

Montgomery County was named after the well-known Major General Richard Montgomery. Richard Montgomery served in the Continental Army during the American Revolution War. Eight months before the county was named after him, Richard Montgomery died in Quebec City while attempting an unsuccessful invasion of the Province of Quebec. Surprisingly, General Montgomery had never set foot on the land that would later bear his name. Despite some attempts to change the county's name in later years, Montgomery County still bears the title to date.