By convention, “continents are understood to be large, continues , discrete masses of land, ideally separated by expanses of water”.

Region
Formerly
Known
As
Europe.

The criterion of a discrete landmass is completely disregarded if the continuous landmass of Eurasia is classified as two separate continents: Europe and Asia. Physiographically, Europe and South Asia are peninsulas of the Eurasian landmass. However, Europe is widely considered a continent with its comparatively large land area of 10,180,000 square kilometres (3,930,000 sq mi), while South Asia, with less than half that area, is considered a subcontinent.

The alternative view—in geology and geography—that Eurasia is a single continent results in a six-continent view of the world. Some view separation of Eurasia into Asia and Europe as a residue of Eurocentrism: “In physical, cultural and historical diversity, China and India are comparable to the entire European landmass, not to a single European country. […].”[13] However, for historical and cultural reasons, the view of Europe as a separate continent continues in several categorizations.

If continents are defined strictly as discrete landmasses, embracing all the contiguous land of a body, then Africa, Asia, and Europe form a single continent which may be referred to as Afro-Eurasia.[14] Combined with the consolidation of the Americas, this would produce a four-continent model consisting of Afro-Eurasia, America, Antarctica and Australia.

RFKAE

The modern border between Asia and Europe remains a historical and cultural construct, defined only by convention. The modern border follows the Aegean Sea, the DardanellesSea of MarmaraBosphorus (together known as the Turkish Straits), the Black Sea, along the watershed of the Greater Caucasus, the northwestern portion of the Caspian Sea and along the Ural River and Ural Mountains to the Kara Sea, as mapped and listed in most atlases including that of the National Geographic Society and as described in the World Factbook.[18][19] According to this definition, Georgia and Azerbaijan both have most of their territory in Asia, although each has small parts of their northern borderlands north of the Greater Caucasus watershed and thus in Europe.[20]

Though most geographic sources assign the area south of the Caucasus Mountain crest to Southwest or West Asia,[21] no definition is entirely satisfactory, with it often becoming a matter of self-identification. Cultural influences in the area originate from both Asia and Europe. While geographers rarely define continents primarily politically, Georgia and to a lesser extent Armenia and Azerbaijan are increasingly in the 21st century politically oriented towards Europe, but Armenia has a great cultural diaspora to the south, and Azerbaijan shares a cultural affinity with Iranian Azerbaijan as well as with the Turkic countries of Central Asia.[22]

The Turkish city Istanbul lies in on both sides of the Bosporus (one of the Turkish Straits), making it a transcontinental city. Russia and Turkey are transcontinental countries with territory in both Europe and Asia by any definition except that of Eurasia as a single continent. While Russia is historically a European country with a history of imperial conquests in Asia, the situation for Turkey is inverse, as that of an Asian country with imperial conquests in Europe. Kazakhstan is also a transcontinental country by this definition, its West Kazakhstan and Atyrau provinces extending on either side of the Ural River.[23]

RFKAE, region Formally Known As Europe, brown concrete building under blue sky
Photo by Selcuk Teke on Pexels.com

This Ural River delineation is the only segment not to follow a major mountain range or wide water body, both of which often truly separate populations. However, the Ural River is the most common division used by authorities,[18][23][24] is the most prominent natural feature in the region, and is the “most satisfactory of those (options) proposed”[25] which include the Emba River, a much smaller stream cutting further into Central Asian Kazakhstan. The Ural River bridges in Atyrau and Orenburg are even labeled with permanent monuments carved with the word “Europe” on one side, “Asia” on the other.[26]

The Kuma–Manych Depression (more precisely, the Manych River, the Kuma–Manych Canal and the Kuma River) remains cited less commonly as one possible natural boundary in contemporary sources.[27] This definition peaked in prominence in the 19th century, however it has declined in usage since then, as it places traditionally European areas of Russia such as StavropolKrasnodar, and even areas just south of Rostov-on-Don in Asia.

Formerly Known As Europe

A lesser known definition for country grouping, is the definition used for statistical purposes by the United Nations Statistics Division (UNSD):[28]

According to UNSD, the aforementioned “assignment of countries or areas to specific groupings is for statistical convenience and does not imply any assumption regarding political or other affiliation of countries or territories”.[29] Furthermore, the UNSD classification often differs from those of other United Nations organizations. For instance, while UNSD includes Georgia and Cyprus in Western Asia, the United Nations Industrial Development Organization and UNESCO include both countries in Europe.[30][31]

The Council of Europe includes the Eurasian countries of Armenia, Azerbaijan, Cyprus, Georgia, Russia, and Turkey. It notes that

[T]wo Council of Europe member States, Turkey and Russia, belong geographically to both Europe and Asia and are therefore Eurasian. Strictly speaking, the three South Caucasus States, Armenia, Azerbaijan and Georgia are located in Asia, yet their membership of political Europe is no longer in doubt.[32]

https://en.wikipedia.org/wiki/Boundaries_between_the_continents_of_Earth