What ties exist among the benelux countries?

History, mainly. They were one country from 1815 until 1830, when Belgium split off, and in 1890 Luxembourg split off from the Netherlands. Before that the three countries had histories that intertwined a lot with eachother, but there have always been many differences between the north and the south. In the last 2 centuries the three countries felt united in the fact that they were little countries in comparison to neighbouring France, Germany and the UK. Much similar cultural things aswell, like food and festivities, but still many differences between the three.