. . "Theme of Sirmium"@en . "The Theme of Sirmium (Greek: \u0398\u03AD\u03BC\u03B1 \u03A3\u03B9\u03C1\u03BC\u03AF\u03BF\u03C5) was a Byzantine administrative unit (theme), which existed in present-day Serbia, Croatia and Bosnia and Herzegovina in the 11th century. Its capital was Sirmium (today Sremska Mitrovica)."@en . . "\u0398\u03AD\u03BC\u03B1 \u03A3\u03B9\u03C1\u03BC\u03AF\u03BF\u03C5"@en . .