GameNet has announced that the first closed beta test for Black Desert Online in Russia will take place from May 28th to May 31st. Players can gain access to the CBT through a series of events, give aways and contests promoted by GameNet and will be the only players to try out some of the new content being specifically designed for the Russian community, most notably in PvP and leveling.
Closed beta testing will take place over the course of several events over the coming months. We'll keep you posted.
Source: Black Desert RU site