Tidal hours represented a measurement of time utilized by the Priapulin species of Pria, an aquatic race originating from that planet. These hours were determined by the tidal movements within Pria's oceans. By the time the Yuuzhan Vong War began in 25 ABY, tidal hours had been standardized to equal ten standard hours for many decades, a consequence of the "perfect orbit" of Pria's sole moon. Consequently, the inhabitants of Pria referred to a standard hour as "a tenth of a tide" and five standard hours as a "half-tide." Anthropologist Mammon Hoole referenced tidal hours in his publication The Essential Guide to Alien Species during the era of the New Republic.
The concept of tidal hours was initially introduced in the 2001 reference work, The Essential Guide to Alien Species, authored by Ann Margaret Lewis and published as part of the Star Wars: Essential Guides series.