Libau RENTAP’s fort (Kuta) at Bukit Sadok was regarded by the Dayak Ibans as impregnable. Since Libau RENTAP was retreat from the lost of his last fort at Sungai Lang, he had strengthened his position at Bukit Sadok. In the Dayak Iban legends and songs the Dayak Iban community mentioned that the Bukit Sadok as a mountain so inaccesible and it was protected by the legendary characters of Panggau Libau, namely Keling and Bunga Nuing, Laja and Bunga Jawa, and many others, that no enemy would ever dare to attack it. Libau RENTAP had gathered together all the Dayak Iban from all along the Skrang River who were faithful to him and those in the upper Saribas River who offered him aid so long as he occupied the top of Bukit Sadok which stood as an unapproachable centre far removed from danger, and to which they could all retire in case of need from the rule of the White Man.
Libau RENTAP was given the tittle of “RAJA ULU” by all of the Dayak Iban warrior chief and Bukit Sadok was the centre of all opposition to the rule of the Rajah of Sarawak, James Brooke. Libau RENTAP fort (Kuta) at Bukit Sadok was about 2,725 feet above the sea level and almost in accessible on every side because of the steep cliff. Libau RENTAP was satisfied that his fort (Kuta) was very strong and could not be conquer by his enemies. The Dayak Iban was thus boasted to themselves that : “The White Man are powerful, having arms and ships at sea, but it is only we who are the Dayak Iban, who can walk and fight on land and clamber mountains.”