The Assyrian Mastiff, was a landrace of dog found in Assyria. This dog was often used as a livestock guardian against predators, as well as for lion and wild horse-hunting. The modern Assyrian Shepherd (in more recent years also known as the Kurdish Mastiff) is likely to be a descendant of the Assyrian mastiff.
The name is most likely derived from the images of this type of dog that appear in Assyrian, Babylonian and other Mesopotamian reliefs dating from the 10th to 6th century BCE Neo-Assyrian Empire.
Adapted from Wikipedia, CC BY-SA 4.0 — https://en.wikipedia.org/wiki/Assyrian_Mastiff