The primary historical setting of Assassin's Creed Syndicate is 1868.
Syndicate takes place in London during the Industrial Revolution, near the end of the Victorian era. The Frye twins, Jacob and Evie, arrive in the city and work to weaken Templar control while confronting criminal gangs and industrial exploitation.
The year 1868 places the story after the major events of Unity's French Revolution setting and before the twentieth-century portions of the franchise. London is divided into districts controlled by influential figures, and the twins gradually bring those areas under Assassin influence.
The game launched in 2015, but its release year is not the same as its historical setting. The date 1868 refers to the main narrative period, while brief sequences and downloadable content can involve additional contexts.