The first group of colonists , known as the Old Three Hundred , arrived in 1822 .
The first group of colonists , known as the Old Three Hundred , settled along the Brazos River , ranging from the Gulf of Mexico to near present - day Dallas .
The first group of colonists , known as the Old Three Hundred , arrived in 1822 and settled along the Brazos River , ranging from the Gulf of Mexico to near present - day Dallas .