Star Trek: 11 Things You Didn’t Know About The Kzinti
3. They Fought Several Wars With Earth
As established by Sulu in The Slaver Weapon, the Kzinti fought four wars against Humanity in the late 21st century. They lost every one due to humans having superior technology.
In Larry Niven's original story, The Soft Weapon, the first war between the Kzinti and humanity was fought using sublight spacecraft and humans only prevailed because they acquired technology that permitted faster-than-light travel.
This doesn't quite gel with the known Star Trek timeline in which humanity's first contact with extraterrestrials occurred immediately after Zefram Cochrane's successful test of warp drive in 2063. In the Star Trek: Voyager episode Friendship One, it was stated that the episode's titular probe was launched in 2067 when humans were still ignorant of the horrors that awaited them in deep space. So it must've been sometime after that that humanity encountered the Kzinti.
During the wars, some Kzinti ate the flesh of humans they managed to kill and apparently liked it. Chuft-Captain, the commander of the Kzinti expedition in The Slaver Weapon, used this as a threat against the Enterprise crew members.