T.S. Eliot's bleak poem, The Waste Land, ends with Shantih shantih shantih. The word, according to him, can be feebly translated to the Peace which passeth understanding.
The preceding line in the poem is also from the Upanishads and reads Datta. Dayadhvam. Damyata.
There is some debate as to why Eliot dropped the om that customarily precedes the shanti, shanti, shantihi.
Connotations
Indian connection