Italy was easier and safer than that by land with Serbia. The long, formidable ranges of limestone mountains which divide the Serbian interior from the Adriatic in almost unbroken and parallel lines have always been a barrier to the extension of Serb power to the coast, and an obstacle to free commercial intercourse. Nevertheless Ragusa was a great trade centre, and one of the factors which most contributed to the economic strength of the Serbian Empire. The first of the Nemanja dynasty was Stephen, whose title was still only _Veliki Župan_; he extended Serb territory southwards at the expense of the Greeks, especially after the death of Manuel Comnenus in 1180. He also persecuted the Bogomils, who took refuge in large numbers in the adjacent Serb state of Bosnia. Like many other Serbian rulers, he abdicated in later life in favour of his younger son, Stephen, called Nemanjié (= Nemanya’s son), and himself became a monk (1196), travelling for this purpose to Mount Athos, the great monastic centre and home of theological learning of the Eastern Church. There he saw his youngest son, who some years previously had also journeyed thither and entered a monastery, taking the name of Sava. It was the custom for every Serbian ruler to found a sort of memorial church, for the welfare of his own soul, before his death, and to decorate and endow it lavishly. Stephen and his son together superintended the erection in this sense of the church and monastery of Hilandar on Mount Athos, which became a famous centre of Serbian church life. Stephen died shortly after the completion of the building in 1199, and was buried in it, but in 1207 he was reinterred in the monastery of Studenica, in Serbia, also founded by him.