The Bilen (also variously transcribed as Blin, and also formerly known as the Bogos^[2] or Northern Agaw^[3]) are a Cushitic ethnic group in Eritrea. They are primarily concentrated in central Eritrea, in and around the city of Keren and further south toward Asmara, the nation's capital. They are split into two sub-tribes; Bet Tarqe, Bet Tawqe which are split into further clans known as Hissat. The Tawke has six whereas the Tarke has five which each are divided into smaller kinship groups.^[4]

According to local oral tradition, the Bilen migrated to the Eritrean plateau from Lasta around the 9th or 10th century led by Gebre Tarqe.^[5][6] A second wave of migration may have occurred according to historians during the fall of the Zagwe dynasty in 1270. In the 14th century, other groups with different origins were also integrated into the Bilen, such as the Bet Tawqe from Hamasien.^[7]

The Bilen are first mention in the 14th century text, the Acts of Ewostatewos. Local traditions suggest that they recognized the authority of some Ethiopian Emperors. The period of Funj domination over neighboring areas is also remembered as a time of stability for the Bilen.^[8]

At the end of the Zemene Mesafint, the Bilen were largely autonomous but accepted the suzerainty of the Christian governor of Hamasien. Many Bilen, however, later converted to Islam in response to Egyptian raids. During this period, Egyptian sources refer to the Bilen area as "Kustan" (from "kréstyan," meaning "Christian") and considered it a dependency of the Mudiriyah of Taka, conducting raids against them in 1850, 1854, 1862–63, and 1867. The Ethiopian warlord Dejazmach Wube Haile Maryam also led several devastating raids against the Bilen from 1844–1849. Facing increasing pressure in their borderland existence, the Bilen began seeking protection from external powers and changed their religious affiliations.^[9]

In the early 1850s, a Catholic mission led by Giovanni Stella was established in Keren. The permanent presence of the Catholic Lazarist mission had a lasting influence on the Bilen, and Keren became one of the few centers of the Apostolic Vicariate of Abyssinia. The French established a permanent consulate at the coast and declared the Bilen their protégés. In the 1860s, the Bilen territory became a de facto French protectorate. Traditional feuds with cattle-raiding groups from Barka (a term for the inhabitants of the Barka lowlands), who were Egyptian subjects, led to reparations paid by the Egyptian government to the French, who then redistributed them among the Bilen. Stella then established an Italian agricultural colony in the area (the "Colonia Italo-Africana di Sciotel", 1867–69), however Stella died in 1869 after which the colony soon disintegrated.^[10]

In 1865–66, the Egyptians took over the Ottoman province of Massawa and also laid claim to Keren. Some Bilen elders reportedly sought Egyptian protection, which Werner Munzinger, the Egyptian governor of Massawa since 1871 (who was married to a Bilen woman), used as justification to occupy Keren on July 2, 1872. Over the following years, the new government effectively pacified the Bilen area (1872–75). In 1875, when war between Egypt and Ethiopia became imminent, Egyptian troops from Massawa were concentrated in the Bogos area. Amid power struggles in Hamasien, the rebellious Ras Woldemichael Solomon established himself among the Bilen (1876–79). However, with Egypt weakened by the war, Ras Alula, governor of the Mereb Melash, raided the Bilen and even attacked areas surrounding the Egyptian fort of Sanhit in Keren, forcibly collecting tribute.^[11]

Emperor Yohannes IV launched an active diplomatic campaign to convince European powers, including high-ranking Egyptian officials like General Charles George Gordon, that the Bilen territory should be ceded to Ethiopia. The Anglo-Egyptian Hewett Treaty of 1884 officially transferred the Bogos territory to Emperor Yohannes IV, and most of it was occupied by Ras Alula as his northernmost province. However, in 1888, the Italians, who had declared a protectorate over the Red Sea coast, annexed the Bilen area. In 1890, it was incorporated into the Zona di Cheren of the newly established Italian Eritrea.^[12]

The Italians maintained the traditional Bilen system of governance and ruled through the different clans. It was only in 1932 that they attempted to appoint leaders for both the Bet Tarqe and Bet Taqwe clans, but this move was met with strong opposition.^[13]

During the Eritrean War of Independence (1961–91), the Bilen remained staunchly loyal to the Eritrean Liberation Front (ELF), though they became underrepresented in the Eritrean People's Liberation Front (EPLF) and the later Eritrean government.^[14]

According to a 2006 estimate, the total population of the Bilen was around 91,000.^[15] The Bilens comprise around two percent of the population of Eritrea.^[16] The vast majority of the Bilen live in Eritrea but some also live in Ethiopia and Djibouti.^[15]

The Bilen practice both Islam and Christianity. Around two-thirds of the Bilen are Muslim while the rest are Christians.^[15] Muslim adherents mainly inhabit rural areas and have intermingled with the adjacent Tigre, while Christian Bilen tend to reside in urban areas and have intermingled with the Tigrinya People (Biher-Tigrinya).^[3] Sunni Islam is followed by half of the Bilen, with the other half adhering to Christianity of various denominations.^[5][6] The religious diversity of the Bilen has aided the peaceful coexistence among them with little conflict arising due to religious differences.^[5]

The Bilen were originally Coptic Christians. In the mid to late 19th century during the Egyptian invasion of the Keren highlands (1860-1876) the Bet Tawqe clan accepted Islam, adopting the faith of their new overlords. The Bet Tarqe clan of the Bilen adopted Catholicism at the hands of French missionaries who offered to protect them from Beni-Amer raids in the area during the second half of the 19th century. There are a few mission-converted Protestants and few Bilen have retained their old Coptic Orthodox beliefs.^[4][15]

The traditional livelihood of most Bilen consisted of pastoralism. However, the recent migration of other groups into the area resulted in the Bilens taking up other occupations including farming. Most modern Bilen are animal herders and farmers.^[6]

The Bilen speak the Bilen language as a mother tongue, which belongs to the Cushitic branch of the Afro-Asiatic language family. Many also speak other Afro-Asiatic languages such as Tigre and Tigrinya. In addition, younger Bilen often employ Arabic words and expressions in their everyday speech.^[3]