Simplify the following text for a Grade 11 native English-speaking person.
Original: From these unified Netherlands , seven northern provinces would form the Republic of the Seven United Provinces in the 17th century , namely Holland , Zeeland , Gelderland , Utrecht , Friesland , Overijssel and Groningen .
Simplified: From these unified Netherlands , seven northern provinces formed the Republic of the Seven United Provinces in the 16th century . These were Holland , Zeeland , Gelderland , Utrecht , Friesland , Overijssel and Groningen .