Proper  documentation  of  the  area  begins  with  the Portuguese, the first  European  power  to seize control of the maritime districts of Sri Lanka. During their  administration from  1505 to 1656, t he Portuguese carefully compiled lists of villages  so  that  the  task  of  collecting  taxes  would be made easier. These lists (thombos)  contained  not  merely  names  but detailed descriptions of the location and extent of each village as well as  of  the  agricultural  produce, including timber and  fruit  trees,  fount  there.  The antiquity of certain  village is made  manifest in these  Portuguese  records  for  modern  towns  and villages in the Sinharaja region such  as  Kalawana  and  Pothupitiya  still  bear  the same name they had when the Portuguese wrote about them four centuries ago.

                The next European power, the Dutch, (1656 - 1796) not only took over and  maintained  these  records  but  also made  a more  important  contribution  of charting  the area  on  maps. By 1789, the Sinharaja region  had  been  demarcated on  a  map  that also traced  the course  of the two large rivers, the Gin Ganga and the Kalu Ganga which had their head waters in the Sinharaja. 

                The  Dutch  maps  made systematic exploration easier during the British colonial   period   (1796 - 1948)   that  followed.  Under  British  rule,  a  number  of expeditions  were  mounted  for  a variety of purposes. Some, especially the official surveys,  were  purely  commercial  in nature. The 1873 exploration by James Gunn, The  example  was meant to ascertain the suitability of the region for raising coffee plantations  and  for  the  possible  exploration of its timber resources. On the other hands,   George  Henry  Thwaites   in   the   1850's  was  responsible  for  the  first comprehensive   documentation   of   the  island's  flora  in  "Enumeratio Plantarum Zelaniae"  (1858 -1864)  which  made  numerous  references  to plants found in the Sinharaja.  The most  notable of early British explorations of the Sinharaja was that of  the  soldier-ornithologist, Captain Vincent Legge who incorporated the result of his  forays  into  his work, "The History of the Birds of Ceylon" (1880). In the latter part  of  the  nineteenth  century,  foresters, botanists  and surveyors occasionally visited the flora began to appear in recognized journals. For instance, The forest by Frederick  Lewis  a  forester,  appeared  in  1896 in  "The Ceylon Forester".  Further references  to  plant  life in Sinharaja appeared in Henry Trimen's "The Handbook to the Flora of Ceylon" (1893 - 1900).

                   As far back as 1840, the Sinharaja become Crown Property under the Wasteland  Ordinance,  Which  declared  all  forest  and unoccupied or uncultivated land in the country as crown land. In May 1875, Under an amended ordinance aimed at regulating the felling and removal of timber from land an area of 6,000 acres was declared   as   the   reserved  forest  of "Sinharaja Mukalana".  (Ceylon Government Gazette No. 4046 dated 8th May,1875.)