Emain Macha between history and legend:
During Iron Age, Emain Macha was the main city of Ulaids, the population that gave the name to Ulster (one of the four regions of Ireland).and this is why it’s one of the main scenario of the “Cycle of Ulster”, among the biggest and more important cycles in irish mythology. From here was reigning the famous king Conchobar Mac Nessa, at war with the Confederacy of the rest of Ireland, led from King Ailill of Connaught and the powerful warrior-queen Medb  (the famous Shelley’s Queen Mab).
There are two different legends on the origin of the name “Emain Macha”, both tied to the foundation of the site by the goddess Macha:
- “The brooch of Macha” : Macha, daughter and last heir of Aedh, king of Ulster, asks to become sovereign, but that’s prevented because she is a woman. She decides so to fight those who didn’t want to give her the throne, Cimbaeth and Dithorba. Macha wins and then reigns for seven years. In the while Dithorba dies, leaving five sons. When seven years are passed, Dithorba’s sons ask for sovereignty, but Macha doens’t want to give them since she had to conquer her place with war and not had it for her right. There’s another war: Macha wins again and Dithorba’s sons go in exile in the wild Connacht. Then she marries Cimbaeth and gives him the control of her soldiers.
At this point, she decides to go to find Dithorba’s sons: she covers herself with clothes that make her seem a leper and in this guise reach them. One of the men, even despite her look, choses to have her, so they go together in the wood. When Macha returns alone, another brother asks her where the man is and she answers that he felt ashamed to had a leper and so he remained hidden in the woods. The other brothers, one by one, don’t disdain anyway her company and so they go in the wood alone with her, that actually is tying them with her strength and magic and making them prisoners. When they are back to the Ulaids, these want the men dead, but Macha says: ” Not so, because it would be the defilement of the righteousness of a sovereign to me; but they shall be condemned to slavery, and shall raise a Rath around me, and it shall be the chief city of Ulster for ever”. After said this, with her golden brooche she tracks the perimeter on the ground: the one of Emain Macha.
2. “Macha’s Twins” : one day a beautiful woman, Macha, arrived at the house of the widower Crunniuc mac Agnomain, and he fell in love with her. So Macha went to live to his house and she became pregnant. When her pregnancy was near the end, Crunniuc prepared to go to the fair. Macha reminded him to not talk too much, but this didn’t happen: during the horse race, the crowd shouted out that no one could beat the king’s horses; Crunniuc said that his wife could, so they asked for proof and the beautiful Macha was called. As she arrived, they took her in front of the king and he asked her name; she answered: “My name, and the name of my offspring will be given to this place. I am Macha, daughter of Sainrith mac Imbaith”.
After this, the race began. Macha won but, as the king’s chariot reached the finish line, she gave birth to twins. In the midst of the labor, Macha cursed all those who could hear her pain laments: they’d suffer labor pain for five days and four nights as they were in greatest need. After that, the city took the name of Emain Macha, “Macha’s twins”, and her curse lasted for nine generations.
 “The Gods of the Celts” – Miranda Green
 Book of Leinster – Lebor Laignech
 Táin Bó Cúailnge