The Origin and development of the bully breeds and molossers stem across several continents and over several centuries. Dispersed by traders, used in wars and migrating with caravans;
These breeds were selectively bred to accomplish a specific task from the sport of bull and bear baiting to guardians of estates to war dogs.

This is where the creation of mastiffs, bull breeds, bull and terriers would all stem from.
Dogs of ancient times were not purebred breeds as we know them by today’s standards as there was no written standards for breed type nor were there registries and clubs dedicated to developing a breeds purity.
A mix of dogs would exhibit a certain “look” and would then be bred for specific traits, matching like to like and focusing on abilities, function and temperament.

The name Molosser also called Molossians, Molossoids and Molossi are dogs sharing common traits such as heavy bones, pendant ears, a relatively short well-muscled neck, and a short muzzle. Originating from Epirus south of Present Albania, The name itself derives from Molossia an area of ancient Epirus where the large shepherd dog known as a Molossus would be a founding ancestor to the great mastiffs of today. Other ancient breeds such as Bullenbeisers, Spanish Alaunt, Bandogges, boarhounds, pugnances (war dogs of Briton) would all play key roles in the history of the breeds we know today influencing their existence through man’s use of them.

The modern breeds we know today were founded in their country of origin, all being selectively and carefully developed by their countrymen for a specific task:
The Neapolitan mastiff was used as a war dog by the Romans, further back in its history they were utilized for their great strength against lions and bear baiting. The Dogue de Bordeaux stemming from the French getting its name from the Bordeaux area of France was used as a utilitarian draft dog for hauling cargo on carts, hunt wild boars as well as used as a guardian for vineyards and estates of the elite.

Bullmastiffs as the “poachers dog” utilized to hunt poachers and thieves, as well as make a fine guardian for its masters.
The British Bulldog was developed in Britain. It would been influential breed in the background of many bully breeds. It was used for bull and bear baiting in the early 1800’s which later would become outlawed by 1835. 
Many mini molossers such as French bulldogs, pugs, bostons, bull and terrier breeds were developed through selectively breeding the smaller molossers keeping with the brachcephalic features the short snouts, round heads and blocky bodies would become a common feature among the mini bully breeds. The Staffordshire Bull terrier known as the ” Nanny Dog” was developed in England known for its affectionate and protective nature for children, it would later be used in the development of the American Pitbull terrier after its importation into the Americas ,it would be known for its skill in the blood-sport of dog fighting. This sport would be banned in the 1860’s but is still practiced illegally underground as well as in other countries to this day.

Many new bully breeds would be developed through the APBT such as the American Bully, the Micro exotic bully and when crossed with mastiffs, would create modern day Bandogs. The Cane corso, Presa Canario, Boerboel and American bulldog are also large breed bully breeds with similar characteristics of the molossian family: strong drive, strong willed, territorial, extreme loyalty to its family and courageous when under threat make for ideal guard dogs and hunting companions. Other breeds such as the Boxer, Great Dane, Rottweiler, Dogo Argentino, English Bull Terrier all share features passed down from their ancestral predecessors.

Each breed carries its own distinct historical record of development from its country of origin. Throughout the years breeds have been imported and exported around the world influencing the country it inhabits; bloodlines emerged and breed standards were set. The breeds we know today became uniform and consistent and purebreds emerged.