who were the first pilgrims (in other words they were members of what group)
English Puritans
Plymouth Colony
English Puritans 
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Plymouth Colony [SEP] Origin
Plymouth Colony was founded by a group of English Puritans who came to be known as the "Pilgrims". The core group (roughly 40% of the adults and 56% of the family groupings) were part of a congregation led by William Bradford. They began to feel the pressures of religious persecution while still in the English village of Scrooby, near East Retford, Nottinghamshire. In 1607, Archbishop Tobias Matthew raided homes and imprisoned several members of the congregation. The congregation left England in 1608 and emigrated to the Netherlands, settling first in Amsterdam and then in Leiden. In Leiden, the congregation gained the freedom to worship as they chose, but Dutch society was unfamiliar to them.