Six Vilayets
The Six Vilayets, the Six Provinces, or the Six Armenian Vilayets were the main Armenian-populated vilayets of the Ottoman Empire and, together, consitute most of Western Armenia. These were Van, Erzurum, Mamuret-ul-Aziz, Bitlis, Diyarbekir and Sivas.
Name
The term Six Armenian Vilayets was a diplomatic usage referring to the Ottoman provinces with substantial Armenian populations. In fact, this term was known in the diplomatic language of the time as the area for which a number of Great Powers wished reforms for the benefit of the Armenians. The term was based on the official language adopted by the signatories of the Treaty of Berlin, the final act of the Congress of Berlin in 1878, in Article LXI: “The Sublime Porte undertakes to carry out, without further delay, the improvements and reforms demanded by local requirements in the provinces inhabited by the Armenians, and to guarantee their security against the Circassians and Kurds.”Population
Ethnic groups
;Statistical analysis of the racial elements in the Ottoman provinces by the Armenian Patriarch of Constantinople, 1912Note: The analysis excludes certain portions of these provinces where Armenians are only a minor element. These portions are as follows: Hakkiari, in the Vilayet of Van; the south of Sairt, in the Vilayet of Bitlis; the south of the Vilayet of Diyarbekir; the south of Malatia, in the Vilayet of Mamuret-ul-Aziz; the north-west and west of the Vilayet of Sivas.
;Ottoman official population statistics, 1914
Note: The Ottoman population statistics doesn't give information for separate Muslim ethnic groups such as the Turks, Kurds, Circassians, etc.
The official Ottoman population statistics of 1914 that were based on an earlier census underestimated the number of ethnic minorities, including the number of Armenians. The Ottoman figures didn't define any ethnic groups, only religious ones. So the “Armenian” population as counted by the authorities only tallied ethnic Armenians who were also adherents of the Armenian Apostolic Church. Ethnic Armenians who professed the Muslim faith, which by that time had grown in number, were counted only as “Muslims”, while Armenian Protestants, just as Pontic Greeks, Caucasus Greeks, and Laz, were counted as "others".
| Ethnic groups | Bitlis | Diyarbekir | Erzurum | Mamuret-ul-Aziz | Sivas | Van | TOTAL | % |
| Muslims | 309,999 | 492,101 | 673,297 | 446,376 | 939,735 | 179,380 | 3,040,888 | 79.6 |
| Armenians | 119,132 | 65,850 | 136,618 | 87,862 | 151,674 | 67,792 | 628,928 | 16.5 |
| Others | 44,348 | 4,020 | 5,797 | 4,047 | 78,173 | 11,969 | 148,354 | 3.9 |
| TOTAL | 473,479 | 561,971 | 815,712 | 538,285 | 1,169,582 | 259,141 | 3,818,170 | 100 |
Largest cities
All figures are as of early 20th century.| City | Vilayet | Population | Armenians | % |
| Van | Van Vilayet | 40,000 | 25,000 | 62.5% |
| Sivas | Sivas Vilayet | 60,000 | 30,000 | 50% |
| Erzurum | Erzurum Vilayet | 60,000 | 15,000 | 25% |
| Mezereh | Vilayet of Mamuret-ul-Aziz | 12,000 | 6,000 | 50% |
| Bitlis | Bitlis Vilayet | 30,000 | 7,000 | 23% |
| Diyarbekir | Diyarbekir Vilayet | 150,000 | 45,000 | 33% |
| Arapgir | Vilayet of Mamuret-ul-Aziz | 20,000 | 10,000 | 50% |
| Malatya | Vilayet of Mamuret-ul-Aziz | 40,000 | 20,000 | 50% |