They originate from the northern Carpathians and still inhabit those areas as well as some others in the Pannonian plain. Their homeland is often referred to as Carpathian Ruthenia though that meaning no longer exactly matches the Places inhabited by Rusyns.
Main groups of Ruthene highlanders in the former Galician Carpathians are called (from west to east):
In contrast to the Ukrainian national movement, modern Ruthenian movement was based on the concept of unity with Russians. In this sense Carpatho-Ruthenians represent typical ethnicity of Borderland and their national awakening is a negation of Ukrainian nationalism.
Carpatho-Ruthenian national movement is especially strong amongst those Ruthenian groups that became early geographically separated from Ukrainian ethnic territory (for example Ruthenian settlers in Serbia (Vojvodina), emigrants in USA and Canada).
Tribe of Ruthenians (also known as Rusins, Rusyns, or Rusnaks) are: Lemkos (Lemoks, Lemkians).
During the rule of the Austro-Hungarian Empire (19th and 20th centuries), some Ruthenians moved to what are now the northern regions of Bosnia, Vojvodina (now Serbia-Montenegro) and Slavonia (now Croatia). There they are called by the name Rusins. Note that until the 1971 Yugoslav census, both Ukrainians (Ukrajinci/Украјинци) and Ruthenians (Rusini/Русини) were recorded collectively as Ruthene, at which point they started being recorded separately, and split up the total number with the Ukrainians forming in a minority; that point is irrelevant however, if one takes into account that Rusins were recorded as a separate nationality by the censuses taken in pre-WWII Poland (see for more detailed examples of that in Cezary Chlebowski's Wachlarz).
With the onset of the Internet, some of the Ruthenian emigrees to the west acquired a vehicle to voice their concerns and try to preserve their separate ethnic and cultural identity.
When the Ruthenes accepted Christianity (and who or what they worshiped before) is a source of some debate, but it clearly occurred prior to the break between Orthodox (Eastern) and Catholic (Western) churches in 1054. Saints Cyril (for whom Russia's Cyrillic alphabet is named) and Methodius are referred to as the "Apostles to the Slavs" and many Ruthenian churches are built in their honor.
Author Paul Robert Magocsi provides one of the most detailed and balanced accounts of Ruthene history in "Our People: Carpatho-Rusyns and Their Descendants in North America" published in 1984. At the time, he recorded that there were approximately 690,000 Carpatho-Rusyn church members in the United States (320,000 in the largest Catholic affiliations, 270,000 in the largest Orthodox affiliations, with a remaining 100,000 in various other Protestant and smaller organizations).
The Ruthenes in the former Yugoslavia are organized in the Eparchy of Krizevci.
Rusyn has been granted official status and codified in Vojvodina (Serbia). Since 1995 it has been recognized and codified as a minority language in Slovakia (in cases where there are at least 20% Rusyns). The Rusyn language in Vojvodina, however, sharing many similarities with Slovak, is sometimes considered a separate (micro)language, and sometimes a dialect of Slovak; see Rusin language for details.
Warning: While reading the sources listed above, as well as sources of Ukrainian and Polish origin, one has to be careful to recognize the underlying interest of each of these groups supporting their own national mythology by selective presentation of information and the inter- and extrapolations favorable to that mythos.