According to Wikipedia:
What is today Blount County was for many thousands of years Indian territory, passed down to the Cherokee tribe that claimed the land upon the arrival of white settlers in the late 18th century. Shortly thereafter, On July 11, 1795, Blount County became the tenth county established in Tennessee, when the Territorial Legislature voted to split adjacent Knox and Jefferson counties. The new county was named for the governor of the state of Tennessee, William Blount, and its county seat, Maryville, was named for his wife Mary Grainger Blount. This establishment, however, did little to settle the differences between white immigrants and Cherokee natives, which was, for the most part, not accomplished until an 1819 treaty.
Throughout its history the boundaries of Blount County have been altered numerous times, most notably in 1870 when a large swath of western Blount was split into Loudon and portions of other counties. Also, the establishment of the Great Smoky Mountains National Park in 1936, while not affecting the territory of Blount County, has significantly impacted the use of southeastern Blount County.