Complex sentence: Because of its interest, the Ottoman Empire supported the Bosnian nobility, led by Tvrtko II. After the Lašvanian battle on Lašva river (in 1415), the Ottomans, together with Hungary became the most powerful factor in the history of the Bosnian state.
Split into simpler sentences: Because of its interest in the Ottoman Empire is supporting the Bosnian nobility, led by Tvrtko II. After Lašvanian battle (1415) (on Lašva river), the Ottomans, with Hungary becoming the most powerful factor in the further history of the Bosnian state.