In terms of Sacred Valley Peru history, much of what has been studied pertains to the Inca Empire, which was centered in the Sacred Valley.  According to Inca Mythology, the first Inca king, Manco Capac, who was born from the sun god Inti at Lake Titicaca around the year 1200 AD, established the Inca Empire at Cusco.  The Kingdom of Cusco would increasingly gain importance, as the Inca slowly, but effectively began to absorb other communities.  The Inca civilization really began to expand in the 1400's, under the rule of Inca Pachacutec.  In and around 1438, Inca expansion increased decidedly.  This was a significant period in Sacred Valley Peru history, as the Cusco Sacred Valley was now the capital of an empire that extended to nearly all of civilized South America.