These stories can be linked to what is known about the Samoa-based Tu'i Manu'a Confederacy, ruled by the holders of the Tu'i Manú'a title, which confederacy likely included much of Western Polynesia and some outliers at the height of its power in the 10th and 11th centuries. Tuvalu is thought to have been visited by Tongans in the mid-13th century and was within Tonga's sphere of influence. The extent of influence of the Tuʻi Tonga line of Tongan kings and the existence of the Tuʻi Tonga Empire which originated in the 10th century is spoken of by the world-famous Captain James Cook during his visits to the Friendly Isles of Tonga. By observing such Pacific nations as Tuvalu and Uvea, the influence of the Tu'i Tonga is quite strong and has had more of an impact in Polynesia and also parts of Micronesia than the Tu'i Manu'a.