The simple answer is that, when it is necessary to group religions, Quakers are generally counted as Protestants.
A more complex answer is that there are many definitions of what it means to be a Quaker and what it means to be a Protestant. Some would say that there are enough differences in belief that the groups should not be lumped together.
The Quakers (aka Friends) are a branch of protestant Christianity.
the pilgrims
By most criteria, the Quakers were (and still are) considered a Protestant denomination. Perhaps you intended to ask, "Why were Quakers persecuted so violently by the Puritans?"
mainly protestant and Quakers
The major religious groups were Protestant Christians, Catholics, and Quakers.
Protestant, Presbyterian, Baptist, Methodist, Anglicans, Quakers, Congregationalists
Quaker, a protestant branch of Christianity. Quakers believe in pacifism, equality, and peace.
There were mostly catholics during the 1600-1700s.
Those are all considered to be Protestant denominations -- though some Baptists do not call themselves Protestant because they did not come out of the Reformation (like Lutherans). Methodists sprang from Anglicanism, and Quakers came from the Church of England.
Quakers,protestant group,founded the Pennsylvania colony to escape persecution ,or harsh treatment in England
The Society of Friends is more commonly known as the Quakers. There are approximately 359,000 Quakers in the world today.
There were many Quakers in Philadelphia in the 1700, but the majority of the population was most likely a mix of Protestant Christians.