Venezuelan surnames and the founder's effect

I generated a little map showing the three most common surnames in every Venezuelan state. There are better  methods to discover population movements based on surnames and yet even this distribution can tell us a little bit about our history.

The top surnames in Táchira and Mérida on the West - the region of the gochos - are a unique pattern in Venezuela: they both have Ramírez and Contreras among the top 3. Trujillo - the Northern most part of the Gocho area has Briceño as most popular surname and Montilla, the third one, is among the top 3 only there.

Falcón has Medina as third most common surname. Finally: Nueva Esparta and Sucre have among the top the surname Salazar.  I am sure if we go back to the XIX century and perhaps earlier we will see some reasons for this distribution.