In Assassin's Creed Origins, Bayek and Aya found the Hidden Ones.
The Hidden Ones are created in Egypt after Bayek and Aya uncover the Order of the Ancients, a secret organization manipulating political power. Their new group is intended to protect ordinary people and oppose the Order from the shadows. The pair also establish rules and symbols that anticipate the later Assassin Brotherhood.
The Hidden Ones are therefore the direct institutional predecessor of the Assassins, not simply another name for the later medieval organization. The term “Assassins” is associated with later periods of the series' history. The Order of Ancients similarly predates the Templars and functions as their historical precursor.
Origins was released in 2017 and takes place mainly in Ptolemaic Egypt. Its story follows Bayek of Siwa and Aya during the final years of Cleopatra's political struggle, while the modern sections return to Layla Hassan.