Continuing K'kree expansionism eventually brought them into conflict with the Hivers and their settled territories. First contact occurred in -2045, and by -2038, several Hiver worlds had been occupied by the K'kree. Naturally enough, a war resulted.
In the first stages of the war, the military technology of the K'kree proved superior; the Hivers were beaten back in defeat. Up until that time, the Hiver Navy had been a small exploration force devoted to scouting operations, actions against local navies without jump-capability, and protection of merchant shipping. At best, it could only undertake rear-guard actions as the Hivers retreated.
After six years, the K'kree slowed their advance in order to occupy and absorb their initial conquests. The Hivers used the opportunity to regroup and upgrade their forces. Between -2023 and -2018, the Hivers established the Hive Federation and embraced many local races as equal members. They created and trained a powerful navy. They recruited and trained a large army (populated primarily with client races). And they put into action a crash project to win the war without a battle.
Selecting several worlds within Kilong Sector deep in the K'kree's Two Thousand Worlds, major secret expeditions were dispatched to work a variety of manipulations on native K'kree populations. Over a period of years (-2018 to -2013), the expeditions were successful in changing altering K'kree culture from its consistent and static mold, introducing such aberrations as meat-based sauce and acceptance of isolation as a recreation.
In -2013, the Hivers succeeded in drawing the K'kree to the negotiating table by hinting that they were ready to surrender. During the discussions, the Federation horrified K'kree negotiators by demonstrating to them the success of their expeditions, and revealing plans to radically alter the K'kree social order if the war were to continue. Several months of serious negotiation (and frantic checking by the K'kree) finally resulted in an armistice which returned the occupied worlds to the Hivers and established a secure border which remains stable to this day.
The K'kree were extremely disturbed by the Hiver tampering with their culture. The four K'kree worlds which had been tampered with were sterilized immediately; they remain interdicted worlds even today.