This is a fairly scarce type of sabre that is found in Mexico and probably dates from the Mexican Civil War.
It is highly recognizable due to the very unique thumb piece on the top of the grip, and its very particular Bowie knife type ricasso made in the tradition of many espada anchas.
This particular example seems to have been made using a reworked US 1864 light cavalry sabre hilt. The grip is covered in what appears to be lizard skin. The whole construction is very solid with no rattle.
The scabbard is in exceptional condition, the leather still very supple and pliable.
A very interesting piece for the collector of unusual pieces.