The Generaliteitslanden were the terroritories that were under the direct command of the States General of the Dutch Republic.
The Dutch Republic was formed in 1579, when seven provinces united forces during the Treaty of Utrecht: Friesland, Groningen, Overijssel, Gelderland, Utrecht, Holland, and Zeeland, plus Drenthe (ruled by Overijssel). The governing body was the States General. The Dutch Republic also included other territories that were under the command of the States General, including:
- Staats-Brabant, largely overlapping with the current province Noord-Brabant
- Staats-Vlaanderen, the southern-most part of the current province of Zeeland, connected to mainland Belgium.
- Staats-Overmaas, mostly located in the southern part of the current province of Limburg and parts of modern Belgium.
- Staats-Opper-Gelre, mostly located in the northern part of the current province of Limburg and parts of modern Germany.
If you have ancestors from this region, you may be able to find records of the town where they lived in the records of the States-General at the National Archives in The Hague. Scans of several annual accounts and tax records are available via the finding aid.
I searched on “Sneek” and found a 1578 “Provisional treaty of the Further Union …” and a 1579 “Treaty of the Closer Union” (which includes mention of Sneek as well as some other cities). This was all under “3. Deputies of the College of the Closer-United Provinces, 1578-1581”. They certainly generated a lot of records.