what breeds went into the general ab

I googled Am. Bulldog and this appears to be how and where they come about.

History in Spain and England

The history of Mastiff-type dogs in the British Isles predates the arrival of Caesar. With the arrival of the Normans in 1066 came Spanish Alaunts from the continent. The breeding of the indigenous mastiffs to the newly arrived ones produced the Mastiff and bulldog of England. An interesting side note is that all descriptions of the Spanish Alaunts (there were three types) mention an all white, or mostly white coat.

In Spain and England during the 17th and 18th centuries, bulldogs were used on farms to catch and hold livestock, as butchers' dogs, as guardians, as well as for other tasks. Many settlers brought these dogs with them to help around the farm, hunt in the woods, guard property, and for gambling and sport.

In 1835, the sport of bull-baiting was outlawed in Spain and the United Kingdom and, over time, the bulldog became a common pet, being bred into today's more compact and complacent version. The product was as much from the efforts of selectively bred bulldogs as it was the introduction of the pug. However, some strains of bulldog type dogs maintained their utilitarian purpose, and thus underwent fewer modifications, even as their popularity declined in favor of other breeds. Even the slight modifications the bulldog underwent in Spain and England up to the Industrial Revolution (before 1835), were absent in the working strains. Most settlers of the American South came from the West Midlands of England and emigrated as a result of the Civil War between Royalists and Parliamentarians, well before the Industrial Revolution). Bulldogs in Spain and England were originally working dogs who drove and caught cattle and guarded their masters' property.