Here is a brief history of RiverClan in each book.
Into The Wild
RiverClan is one of the four clans. They attacked Tigerclaw, Ravenpaw and Redtail at Sunnignrocks. Redtail and deputy Oakheart died. Leopardfur became deputy.
Fire and Ice
In Fire and Ice RiverClan didn't want WindClan to come back. They attacked WindClan with ShadowClan but were defeated by ThunderClan and WindClan. RiverClan attacked Fireheart, Graystripe, Onewhisker and Deadfoot. Whiteclaw died after falling into the gorge. Then Silverstream and Graystripe became mates.
Forest of Secrets
A Dangerous Path
The Darkest Hour