What generation of Pokémon games began with Diamond and Pearl?

Pokémon Diamond and Pearl began Generation IV of the Pokémon video game series. Developed by Game Freak for Nintendo DS, the pair was first released in Japan on September 28, 2006.

The games introduced the Sinnoh region and a new group of Pokémon, including the legendary mascots Dialga and Palkia. They expanded the core series with Nintendo DS features and added wireless capabilities, including online trading and battling through Nintendo Wi-Fi Connection.

Diamond and Pearl followed Generation III’s Ruby, Sapphire, FireRed, and LeafGreen games. They were later followed by Generation V’s Black and White. This generational numbering is based on groups of core games and their new Pokémon, not simply on the order of every Pokémon title released.

The games also connected with earlier Game Boy Advance adventures through a migration feature. Players with compatible hardware could transfer Pokémon into Diamond and Pearl, although the process was one-way and subject to daily limits.