Here an interesting term I didn't hear of before:

Olędrzy (singular: Olęder) is a Polish term used to describe persons, often of Dutch or German origin or ancestry, who lived in settlements in Poland organized under a particular type of law.

The term Olędrzy has been used to describe two related, but slightly different, groups of settlers. First, it describes settlers in Poland from Friesland and the Netherlands, most often of the Mennonite faith, who in the 16th and 17th centuries founded villages in Royal Prussia, along the Vistula River and its tributaries, in Kujawy, Mazovia and Wielkopolska. They possessed knowledge of flood control, and a well-developed agrarian culture. At that time, they were the wealthiest group of peasants. They maintained personal freedom, and their own religion and beliefs. After the First Partition of Poland, some of them emigrated to Ukraine.

Second, in a later period (up to the middle of the 19th century), the term Olędrzy was used to describe settlers of different ethnicities (principally Germans and Poles, at times Scots, Czechs, and Hungarians), who benefited from certain privileges resulting from the law established by the Frisian and Dutch colonists (such as personal freedom [1], long-term or perpetual use of land, and the possibility of transmitting land to heirs). The most important characteristic, however, was collective responsibility of the entire Olęder community for its obligations toward the land owner and the specific character of the community's self-government. [2]. Thus, the distinguishing characteristics of an Olęder settlement are legal, and not ethnic, religious or economic. Consequently, the word Olęder is not synonymous with "Dutch settler."

According to studies conducted so far, from 1527/1547 to 1864 on the terrain of the first Polish republic ("Rzeczpospolita") (later divided into three parts in the Polish partitions), at least 1700 olęder settlements were established. Of those, in at least 300 cases the settlers were ethnic Dutch.[3]. Traces of these settlements are still visible in village architecture, the physical layout of villages, and in the names of villages (Holendry, Olędry, Olendry, etc.)
More at the source:
http://en.wikipedia.org/wiki/Ol%C4%99drzy