Which ethnic groups are you talking about? The French and the Dutch? Belgium used to be part of the Netherlands through 1830. And all of the Netherlands used to be part of the Spanish and Frence empires....
Historically, Belgium, the Netherlands and Luxembourg (along with parts of Northern France and Western Germany) were known as the Low Countries; it once covered a somewhat larger area than the current Benelux group of states. The region was called Belgica in Latin, after the Roman province of Gallia Belgica. From the end of the Middle Ages until the 17th century, the area of Belgium was a prosperous and cosmopolitan centre of commerce and culture. From the 16th century until the Belgian Revolution in 1830, when Belgium seceded from the Netherlands, the area of Belgium served as the battleground between many European powers, causing it to be dubbed the "Battlefield of Europe," a reputation strengthened by both world wars.
With the armed support of revolutionary France, Dutch republicans proclaimed the Batavian Republic, modelled after the French Republic and rendering the Netherlands a unitary state on 19 January 1795. The
stadtholder William V of Orange had fled to England. But from 1806 to 1810, the Kingdom of Holland was set up by Napoleon Bonaparte as a puppet kingdom governed by his brother Louis Bonaparte to control the Netherlands more effectively. However, King Louis Bonaparte tried to serve Dutch interests instead of his brother's, and he was forced to abdicate on 1 July 1810. The Emperor sent in an army and the Netherlands became part of the French Empire until the autumn of 1813, when Napoleon was defeated in the Battle of Leipzig. The south gained independence in 1830 as Belgium, while the personal union between Luxembourg and the Netherlands was severed in 1890, when William III died with no surviving male heirs. Ascendancy laws prevented his daughter Queen Wilhelmina from becoming the next Grand Duchess.
Don't blab about that which you don't know.