3) The Roman Empire was very small by the time it was conquered by the Turks in 1453, consisting of a vassal fiefdom containing most of the Peloponnesus and the capital city Constantinople and a small region around it. The Peloponnesus has an area of 21,5439.6 square kilometers or 8,320.3 square miles. It is smaller than Haiti, and some parts of it were ruled by Venice, making the Despotate of the Morea smaller still. The parts of the empire around Constantinople may may or may not have been enough to make the Roman Empire in it's last period larger than the Haitian Empire. But of course it was the surviving part of the vast Roman Empire.
2) The Thessalonikan realm was very small by the time it was conquered by Nicaea, probably containing only a small area around the capital city. But it was a fragment of the Roman Empire that was originally many times times much larger.
1) Modern Haiti has an area of 27,750 square kilometers or 10,710 square miles. The first and second Haitian Empires probably had very similar areas. Thus they probably count as the smallest empires by constant size all during their existence.
Note: The current official size of Wales is 20,779 Square kilometers or 8,023 square miles. If the rulers of sub Roman Britain claimed to be the rightful successors of Constantine III (see number 8 above), then they might be considered Roman Emperors even when their realm was reduced to the approximate size of modern Wales, or even much smaller. Thus the hypothetical Welsh Roman Empire might have been the smallest empire ever.
Note: At its peak around 1241 the Second Bulgarian Empire had a territory of 477,000 square kilometers or 184,000 square miles. By about 1350, in the reign of Ivan Alexander (r. 1331-1371), Emperor of the Bulgarians and the Romans, the size was down to 137,000 square kilometers or 53,000 square miles.
Ivan Alexander made several of his sons co-emperors at various periods. Ivan Alexander's son Ivan Sracimir became Emperor of Vidin or Badin about 1356, defying his farther's authority. Vidin was conquered by Hungary in 1365, and when Ivan Sracimir regained Vidin in 1369 he had to be an Hungarian vassal. Judging by the map I would guess his empire at Vidin was about 27,400 to 34,250 square kilometers or 10,600 to 13,250 square miles.
The Ottomans conquered southern parts of Bulgaria in the reigns of Ivan Alexander and his son Ivan Shisman (r. 1371-1395). The Bulgarian capital Tarnovo was captured in 1393 and Ivan Shishman was captured in Nicopolis in 1395. The Turks captured Vidin in 1396 and Ivan Sracimir was probably killed in 1397. Fruzhin (d. c. 1460) son of Ivan Shisman and Constantine II (d. 1422), son of Ivan Sracimir, were recognized by the Christian powers as Bulgarian Emperors. They may have regained some Bulgarian lands in the Uprising of Konstantin and Fruzhin which may have lasted from 1404 or 1408 to 1413 or 1418. It is believed by some historians that Constantine II may have retained some lands in Bulgaria until 1422 shortly before his death. In which case Constantine II's last remaining possessions may have been the smallest empire ever.
Note: The Island of Elba has an area of 224 square kilometers or 96 square miles. Thus Napoleon's rule of Elba in 1814-1815 could be called the smallest empire in history. But Article II of the Treaty of Fountainebleau said that Napoleon would retain the title and rank of Emperor for life, and Article III said that the Island of Elba would be an independent principality for life for Napoleon. Thus the title of emperor and rule of Elba were two distinct and separate things.
So these are my thoughts about the smallest empires in history.
2) The Thessalonikan realm was very small by the time it was conquered by Nicaea, probably containing only a small area around the capital city. But it was a fragment of the Roman Empire that was originally many times times much larger.
1) Modern Haiti has an area of 27,750 square kilometers or 10,710 square miles. The first and second Haitian Empires probably had very similar areas. Thus they probably count as the smallest empires by constant size all during their existence.
Note: The current official size of Wales is 20,779 Square kilometers or 8,023 square miles. If the rulers of sub Roman Britain claimed to be the rightful successors of Constantine III (see number 8 above), then they might be considered Roman Emperors even when their realm was reduced to the approximate size of modern Wales, or even much smaller. Thus the hypothetical Welsh Roman Empire might have been the smallest empire ever.
Note: At its peak around 1241 the Second Bulgarian Empire had a territory of 477,000 square kilometers or 184,000 square miles. By about 1350, in the reign of Ivan Alexander (r. 1331-1371), Emperor of the Bulgarians and the Romans, the size was down to 137,000 square kilometers or 53,000 square miles.
Ivan Alexander made several of his sons co-emperors at various periods. Ivan Alexander's son Ivan Sracimir became Emperor of Vidin or Badin about 1356, defying his farther's authority. Vidin was conquered by Hungary in 1365, and when Ivan Sracimir regained Vidin in 1369 he had to be an Hungarian vassal. Judging by the map I would guess his empire at Vidin was about 27,400 to 34,250 square kilometers or 10,600 to 13,250 square miles.
The Ottomans conquered southern parts of Bulgaria in the reigns of Ivan Alexander and his son Ivan Shisman (r. 1371-1395). The Bulgarian capital Tarnovo was captured in 1393 and Ivan Shishman was captured in Nicopolis in 1395. The Turks captured Vidin in 1396 and Ivan Sracimir was probably killed in 1397. Fruzhin (d. c. 1460) son of Ivan Shisman and Constantine II (d. 1422), son of Ivan Sracimir, were recognized by the Christian powers as Bulgarian Emperors. They may have regained some Bulgarian lands in the Uprising of Konstantin and Fruzhin which may have lasted from 1404 or 1408 to 1413 or 1418. It is believed by some historians that Constantine II may have retained some lands in Bulgaria until 1422 shortly before his death. In which case Constantine II's last remaining possessions may have been the smallest empire ever.
Note: The Island of Elba has an area of 224 square kilometers or 96 square miles. Thus Napoleon's rule of Elba in 1814-1815 could be called the smallest empire in history. But Article II of the Treaty of Fountainebleau said that Napoleon would retain the title and rank of Emperor for life, and Article III said that the Island of Elba would be an independent principality for life for Napoleon. Thus the title of emperor and rule of Elba were two distinct and separate things.
So these are my thoughts about the smallest empires in history.