But this Serbian suzerainty vanishes with the dreams of Stephen Dūshan. Shortly after his date the Bans of Bosnia become so powerful that they are able to annex the two important Serbian provinces of Rascia and Zenta, which answers to the modern Montenegro, and to proclaim themselves virtually independent both of the Serbian and Hungarian monarchies. In 1376 the Ban, Stephen Tvartko, was strong enough to extort from his uncle, King Louis of Hungary, permission to assume the royal style—the King of Hungary only reserving the _suprema dominatio_.[79] After half a year spent in preparations, Tvartko, accompanied by his lords spiritual and temporal, and by four representatives from each important town, progressed from his residence of Sutiska to the Monastery of Mileševo, the foundation and burial-place of his uncle and predecessor, but the greater glory of which was that it contained the tomb of the Serbian Apostle, St. Sava. There he was crowned by the hands of the Metropolitan, and assumed the title of Stephen Tvartko, by the grace of God King of Rascia, Bosnia, and Primorie.[80] Stephen Tvartko distinguished his rule by his wisdom and toleration. Though himself leaning in his belief alternately to Greek orthodoxy and Roman Catholicism, he displayed a generous toleration of the Bogomiles; he did much to encourage trade and commerce, and was indeed, after Culin, the first Bosnian prince who struck coins.[81] He succeeded in quelling the insolence of his great nobles who had burst out into rebellion, under the leadership of his brother, and the attendance at his coronation of four representatives from each of his great cities would alone be a striking proof that Bosnia was advancing on the path of constitutional liberty, and was not by any means alien to the civic and industrial impulses of fourteenth-century Europe. Nay, it is certain that, in spite of the prevalence of Bogomilism among the masses, and of the artistically blighting influence of an iconoclastic religion on a rude society, arts of a more æsthetic kind were penetrating among the Bosnian mountains. Nor was it only in the illuminations of heraldry, the embellishment of gold and silver work, and the superb embroidery of sacred vestments that these more refined influences asserted themselves. That munificent patron of South-Sclavonic Art, the present Roman Catholic bishop of Bosnia, has collected in his palace of Diakovar, a series of paintings by Bosnian artists of this and the succeeding century, which reflect the Giottesque revulsion from the wooden Byzantinism which preceded it, and show that Bosnia bade fair to produce a school of artists who might hold a place in the galleries of Europe.[82]