Feudal fragmentation in the context of "Fall of the Serbian Empire"

The Mongol Empire invaded and conquered much of the Kievan Rus' in the mid-13th century, sacking numerous cities such as Ryazan, Yaroslavl, Pereyaslavl and Vladimir, including the largest: Kiev (50,000 inhabitants) and Chernigov (30,000 inhabitants). The siege of Kiev in 1240 by the Mongols is generally held to mark the end of the state of Kievan Rus', which had already been undergoing fragmentation. Many other principalities and urban centres in the northwest and southwest escaped complete destruction or suffered little to no damage from the Mongol invasion, including Galicia–Volhynia, Pskov, Smolensk, Polotsk, Vitebsk, and probably Rostov and Uglich.

The Mongol campaign was heralded by the Battle of the Kalka River on 31 May 1223, which resulted in a Mongol victory over the forces of several principalities as well as the remnants of the Cumans under Köten. The Mongols retreated, having gathered their intelligence, which was the purpose of the reconnaissance-in-force. A full-scale invasion by Batu Khan followed, with most of Kievan Rus' overrun in 1236–1238. The Mongols captured Kiev in 1240 and moved west into Hungary and Poland. The heavy losses suffered by the Mongols during the invasion period significantly weakened subsequent campaigns, preventing the ruin of the Holy Roman Empire and more western countries.

The Kingdom of Bosnia (Serbo-Croatian: Kraljevina Bosna / Краљевина Босна), or Bosnian Kingdom (Bosansko kraljevstvo / Босанско краљевство), was a medieval kingdom that lasted for nearly a century, from 1377 to 1463, and evolved out of the Banate of Bosnia, which itself lasted from at least 1154.

King Tvrtko I (r. 1353–91) acquired portions of western Serbia and most of the Adriatic coast south of the Neretva River. During the late part of his reign, Bosnia became one of the strongest states in the Balkan Peninsula. However, feudal fragmentation remained important in Bosnia and the Bosnian nobility held significant power, exercising it at the Stanak meetings where members deliberated on matters such as election of the new king or queen and coronations, foreign policy, sale or cession of territory, contracting and signing treaties with neighboring countries, and military issues.

The Russkaya Pravda (sometimes translated as Rus' Justice, Rus' Truth, or Russian Justice) was the legal code of Kievan Rus' and its principalities during the period of feudal fragmentation. It was written at the beginning of the 12th century and remade during many centuries. The basis of the Russkaya Pravda, the Pravda of Yaroslav, was written at the beginning of the 11th century. The Russkaya Pravda was a main source of the law of Kievan Rus'.

In spite of great influence of Byzantine legislation on the contemporary world, and in spite of great cultural and commercial ties between Byzantium and Kievan Rus', the Russkaya Pravda bore no similarity whatsoever to the law of the Byzantine Empire. The absence of capital and corporal punishment rather reflects Norse jurisprudence.

The Kingdom of Burgundy (Latin: Regnum Burgundiae), also known as the Kingdom of Arles (Latin: Regnum Arleatense), was a realm established in 933 by the unification of Lower Burgundy with the Upper Burgundy. As an independent kingdom, it was ruled by monarchs from the Elder House of Welf until 1032, when it was incorporated into the Holy Roman Empire, becoming one of the empire's three constituent realms, together with the Kingdom of Germany and the Kingdom of Italy. By the 13th century it went through the process of feudal fragmentation, and since the 14th century the imperial rule over the kingdom became mainly nominal, weakening further during the 15th century.

Its territory stretched from the Mediterranean Sea in the south to the High Rhine in the north, and from the Western Alps in the east to the Rhône basin in the west, thus encompassing almost all of the historical Burgundian lands, and roughly corresponding to the present-day French regions of Provence-Alpes-Côte d'Azur, Rhône-Alpes and Franche-Comté, as well as the region of Romandy in western Switzerland.

The Sudebnik of 1497 (Russian: Судебник 1497 года), also known as the Sudebnik of Ivan III (Russian: Судебник Ивана III), was a collection of laws introduced by Ivan III in 1497. It played a big part in the centralisation of the Russian state, the creation of all-Russian legislation, and the elimination of feudal fragmentation. It was later replaced by the Sudebnik of 1550 under Ivan IV.