A bacterial infection struck Ariannus very hard in 2268, which would have destroyed all life on the planet. Fortunately, the USS Enterprise was able to decontaminate Ariannus from orbit. (TOS: "Let That Be Your Last Battlefield").
Timothy Sinclair visited Ariannus in the mid-2350s, and he considered relocating there after his wife's death in 2374. He bought a cabin on northern continent's coastline, where he resided while investigating ruins of an ancient civilization he believed to have originated on Sarpeidon. (Star Trek: Pendragon)