From Rigpa Wiki
The Kalachakra Tantra (Skt. kālacakratantra; Tib. དུས་ཀྱི་འཁོར་ལོ་, dükyi khorlo; Wyl. dus kyi 'khor lo) is one of the main tantras practised by the Sarma or New Translations schools. It has a unique presentation of cosmology. His Holiness the Dalai Lama has given the transmission of the Kalachakra many times around the world for the sake of world peace.