From Bravo Fleet Infobase
The Founders are a liquid based, shape-shifting life-form found in the Gamma Quadrant. Their original homeworld in the Omarion Nebula was rendered uninhabitable in the battle of the Omarion Nebula where the combined forces of the Obsidian Order and the Tal'Shiar bombarded the planet.
The natural state for the Founders is its liquid form of which it has to revert every sixteen hours. It is well known that Founders do not eat however Starfleet Science has speculated that they pull their energy from either subspace or some other realm not yet discovered.
Due to their shape-shifting ability they can become almost any shape although they are limited by their mass and most Founders excluding the hundred that were sent by the Founders into space are able to closely mimic humanoid features to the point that their friends and relatives are unable to tell the difference.
Furthermore, Starfleet Science has established that they have no sense of smell, can survive the coldness of space and can resist disruptor fire with ease. Due to yet unknown reasons, they have the ability to sense the presence of other Founders.
The race makes up the majority of the leadership of the Dominion. They prefer to describe themselves as a drop in the larger ocean (as a drop is an individual as ocean is to the Great Link). Therefore, they don't often have a sense of self. Due to them being a liquid based life form, they revert to this state to blend together and create a link with each other.
It is believed that they can be considered almost immortal as they show no signs of ageing or cellular decay.
The first beginnings of the people who would become the Founders began Millennia ago from the memory of the Great Link. They started to explore the galaxy looking to further their knowledge and to explore much like the Federation. However, everywhere they went they were faced with fear, mistrust and suspicion. Like many races before them the fear to turned to hatred that moved to beatings and finally be hunted like animals.
One of the first races that the Dominion encountered was the Vorta who after saving a Founder from being captured and killed were promised to become powerful beings in the Empire that the Founders were building.
After many years the Founders had enough and retreated to their home-world deep within the Omarion Nebula and founded the Dominion as a way to not only to protect themselves but effectively to unleash retribution on those that had hunted them so brutally.
As the centuries past, the Founders sent their youngest offspring to the far reaches of the galaxy with the genetic compulsion to return home with the information they had attained and share it with the others, so far only two have returned.
What was to become one of the greatest threats to the Federation was formed between the tenth and second Millennium BCE, recruiting the Vorta as high ranking officials in miltary, Scientific and diplomatic fields to run the Dominion daily for the Founders while they created the Jem`Hadar as the fighting force to impose the will of the Dominion on the unsuspecting galaxy.
Being genetically engineered meant that the Dominion could create an army at frightening speed and with the Vorta changed the Dominion from a fledging to a major power. The ability to manufacture the Jem'Hadar, ships and weapons at an incredible rate meant even through wars of Attrition they had an advantage.
Setting plans into motion
It was during the mid 22nd Century, that the Dominion truly imposed its will on the Gamma Quadrant when they encountered a space-faring race called the Teplans who tried to oppose the Founders. The response was nothing short of brutal, sending the Jem'Hadar and crushing their home-world which to set up as an example for others thinking of opposing them they introduced a biological weapon that caused the “Blight”. They also made a similar example of the people of Boranis III.
Dominion Aggression in the Alpha Quadrant
The first contact with the Alpha Quadrant was made by the UFP in late 2370 when the Dominion destroyed a considerable number of colonies and ships from the Alpha Quadrant.
It was claimed that their assault was due to Federation’s incursions into their space but it turned out later to be an attempt by the Dominion to place a female Vorta as a spy within the Federation. Although the attempt was unsuccessful the Dominion War had begun.
Over the next year, they ascertained the strength of the resistance of the Alpha and Beta quadrant powers and made plans accordingly after a number of simulations involving captured members of the Federation. Once they realised that the Federation would destroy the wormhole they adopted a more subtle approach.
They began infiltrating the various powers including the Klingon Empire where they pretended to be a number of high ranking officials, the Romulan Star Empire and the Federation were also affected. They started manoeuvring these powers into several destructive wars to erode their strength.
War in the Alpha Quadrant
In 2373, the Dominion solidified their position by incorporating the Cardassian Empire. Throughout the following months, the Dominion sent massive amounts of ships, weapons and soldiers through the wormhole after a changeling prevented the collapse of the wormhole. During this time the Dominion signed non-aggression treaties against the Miradorn, Bajor, Tholian Assembly and the Romulan Star Empire.
Open war broke out when the Federation mined the entrance of the wormhole to prevent any further reinforcements. The first part of the war, in early 2374, was an unmitigated disaster for the allies that involved almost entirely of retreats. The progress of the war changed when the Allies recaptured DS9 when over two thousand Dominion ships some how disappeared in the Bajoran Wormhole, things got worse for the Dominion when the Romulans abrogated their treaty with them after one of their diplomats died while at DS9. However, conspiracy theories abound that someone in the Federation caused the incident as a ploy to bring in the Romulan Empire. Both the Federation and the Romulan Empire for various reasons deny this.
It was found during this time that Section 31 had infected the Great Link, the very foundation of the Dominion with a mutagenic virus which they were unable to find a cure. The female founder trapped in the Alpha quadrant made an alliance with the Breen Confederacy in an attempt to win the war before she died. However, the terms that were agreed were not palatable to the Cardassians and they rebelled culminating in the Battle of Cardassia which ultimately sealed defeat for the Dominion.
Surrounded by the Allies, the female changeling ordered the remaining ships to fight to the death thinking if they showed weakness the Allies would invade the Gamma Quadrant. However, her mind was quickly changed when she was given the cure to the virus.