Promisoriums were schools constructed by the Sith Lord Arkadia Calimondra during the Republic Dark Age. They were used to indoctrinate younglings in accordance to Arkadia's personal philosophy of revolving sentient beings through different sets of occupations throughout their lifetimes. Ideally, students would work to become as versatile as possible so that as adults they could contribute to her state. These schools were open to individuals of diverse species and also boasted extensive dining facilities. Officially, Arkadia claimed that this policy was used to promote flexibility and versatility among her subjects. Unofficially, this policy served as a insurance that preserved her dictatorial rule by constantly giving them something new to do, thus preventing them from becoming established in one area.

Unlike other Sith Lords who neglected the social welfare of their subjects, Arkadia made it a priority to educate children in her realm and did not forcibly separate them from their parents. This contrasted with her cousins Daiman who exploited children as forced laborers and Odion who had all the children in his realm imprisoned in a series of planet-sized orphanages known as cloisters. In 1032 BBY, Kerra Holt, Brigadier Jarrow Rusher, and the Sullustan student refugee Tan Tengo visited one of these schools during their official tour of Calimondretta, the Arkadianate capital city on Syned. Due to her impoverished background growing up on the Daimanate capital of Darkknell, Tan admired the well-run Promisoriums and almost fell in love with life in the Arkadianate.

The Promisorium on Syned may have been damaged during the Siege of Calimondretta, when Kerra and Rusher escaped from the Arkadianate after Kerra refused to work as an assassin for Arkadia.