Reign
Álmos, according to Gesta Hungarorum, was freely elected by the heads of the seven Hungarian tribes as their "leader and master". Anonymus adds that to ratify Álmos's election, the seven chiefs "swore an oath, confirmed in pagan manner with their own blood spilled in a single vessel". Anonymus says that they also adopted the basic principles of the government, including the hereditary right of Álmos's offsprings to his office and the right of his electors' descendant to have a seat in the prince's council. According to author Pál Engel, this report of the "treaty by blood" (Hungarian: vérszerződés), which reflects its authors' political philosophy rather than actual events, was "often presented by Hungarian historians as the very first manifestation of modern parliamentary thinking in Europe" up until 1945.
In a sharply contrasting narrative from around 950, the Byzantine Emperor Constantine VII Porphyrogenitus states that instead of Álmos, his son Árpád was the first supreme head of the Hungarian tribes, and that Árpád's election was initiated by the Khazar khagan. The emperor says the khagan sent an envoy to the "voivodes" (heads of the Hungarian tribes) after they had been forced by the Pechenegs to leave their dwelling places near the Khazar Khaganate and to settle in a new territory called Etelköz. The khagan was planning to appoint one of the voivodes named Levedi to lead the Hungarian tribes to represent the khagan's interests. Although Levedi refused the khagan's offer, he proposed one of his peers, Álmos or Álmos's son Árpád, to the proposed new position. The khagan accepted Levedi's offer. Upon his initiative, the Hungarians elected their first prince, but they preferred Árpád to his father. The work of Constantine VII, who referred to Magyars as Turks, though considered essentially reliable in its core by Western scholars, is often confusing and filled with legends.
Gyula Kristó and many other historians refute Porphyrogenitus's report of the omission of Álmos in favor of his son, saying that the turul legend connected to Álmos's birth proves his role as the forefather of his dynasty. These historians say that the emperor's account is based on a report by one of Árpád's descendants named Termacsu, who emphasized by this report of Árpád's election that only those descending from Árpád were suitable to lead the Hungarians; other children of Álmos were excluded. András Róna-Tas says that Constantine Porphyrogenitus preserved the memory of a coup d'état organized against Levedi kende by Álmos gyula, who had his own son Árpád elected as sacred ruler in his opponent's place. A late-9th-century Central Asian scholar, Abu Abdallah al-Jayhani—whose works were partially preserved in Ibn Rusta's and other Muslim authors' books—mentions the existence of these two high offices among the Hungarians. He describes the kende as the Hungarians' sacred ruler and the gyula as their military commander. Historians still debate which of the two offices was held by Álmos.
The chagan said to [Levedi]: "We have invited you upon this account, in order that, since you are noble and wise and valorous and first among the [Hungarians], we may appoint you prince of your nation, and you may be obedient to our word and our command." But he, in reply, made answer to the chagan: "Your regard and purpose for me I highly esteem and express to you suitable thanks, but since I am not strong enough for this rule, I cannot obey you; on the other hand, however, there is a voivode other than me, called [Álmos], and he has a son called [Árpád]; let one of these, rather, either that [Álmos] or his son [Árpád], be made prince, and be obedient to your word." That chagan was pleased at this saying, and gave some of his men to go with him, and sent them to the [Hungarians], and after they had talked the matter over with the [Hungarians], the [Hungarians] preferred that [Árpád] should be prince rather than [Álmos] his father, for he was of superior parts and greatly admired for wisdom and counsel and valour, and capable of this rule; and so they made him prince according to the custom, or 'zakanon', of the Chazars, by lifting him upon a shield.
Kristó says that Álmos stood at the head of the Hungarian tribal confederation from around 850. Porphyrogenitus's narration says that he initially accepted the khagan's suzerainty. The Hungarians apparently achieved their independence around 860, since the earliest reports on their plundering raids in Central Europe were recorded thereafter. The Annals of St. Bertin mentions their incursion into Louis the German's realm in 862. Three tribes seceding from the Khazar Khaganate, together known by Porphyrogenitus as "Kabaroi", also joined with the Hungarians in the 860s or 870s. Spinei says that the memory of their arrival was preserved by Anonymus, who mentions "the seven dukes of the Cumans" who "subjected themselves to Prince Álmos" at Kiev.
Anonymus writes of a war between the Hungarians and the Kievan Rus', ending with the victory of the Hungarians, who were commanded by Álmos. The Russian Primary Chronicle refers to a "Hungarian hill" at Kiev in connection with the town's occupation by Oleg of Novgorod in 882. The same chronicle mentions "a castle of Ol'ma" (Олъминъ дворъ) standing on the same hill. George Vernadsky says that this fortress had been named after Álmos, but this theory has not been widely accepted by historians.