In 1708 at Schwarzenu, Germany, Alexander Mack and seven other German believers founded the Bretheren movement. This name comes from Brüder-Gemeinde, or “Community of Brothers”, a name they gave themselves. Through the influence of Pietists (who hated dead orthodoxy, believing Christianity was an experiential faith) and Anabaptists (who were not interested in reforming the church of their day, but starting a New Testament church all-together) this movement started as a reaction to the spiritual stagnancy of the churches in their area. They wanted a spiritual awakening to occur. Their only creed was the New Testament, and they stressed personal discipleship.
They began to meet in homes in order to study the Bible and pray, and Mack became their first leader and minister. This movement spread quickly. They suffered much persecution for “disloyalty to the state” as they did not support the state church. Some of their property was taken from them, and some were thrown in prison. They were driven out of Germany and moved to Germantown, Pennsylvania. Many were converted to this movement as their zeal, honesty, and hard work were noticed by others. Once again, it spread quickly. In the 1790s, Bretheren churches appeared in Kentucky and Ohio. In the 1810s, they appeared in Missouri and Illinois. And in the 1850s, they appeared in California and Oregon.
source: “The Complete Guide to Christian Denominations” by Ron Rhodes