@Asura That's understandable
Basically, Daenerys went to Vaes Dothrak, and demanded all of the Khalasars bend the knee to her and follow her to Westeros, as well as to give up their raiding and slaving ways. The Khals who refused burned, and their followers either fled or burned with them. The rest united into a single Great Khalasar under Daenerys and helped her lift the Siege of Meereen. Then they sailed across the Narrow Sea with the rest of her forces and helped her fight Cersei and Euron before participating in the War for the Dawn.
Of those who survived, some decided to return to the Great Grass Sea, but with her new rules, while others decided to settle in Westeros; mainly in the Riverlands and near King's Landing, primarily as freeriders or riders in service to noble houses while others have started to branch out into different professions. Many went into service in the Royal Army in a light cavalry division called the Night Riders, and the royal family now has Blood Riders to protect them as well as Kingsguard. Back in the Great Grass Sea, the khalasars are divided into those who follow the Great Khaleesi Daenerys and those who want to return the Dothraki to the Old Ways, and these are united under a Great Khal who seeks to make Essos bleed.
Chev