In studying medieval Jewish-Christian relations, one often encounters anxiety. Some Christians asserted that Jewish anxiety was a sign of their cursed status, for example when Jacques de Vitry (c. 1160/70–1240) maintained that certain Jews were fearful and weak because of their ancestors' participation in Jesus's execution. Jewish fear in the face of Christian persecution in poetry and chronicles is a common theme. Finally western Christians imagined all manner of supposed Jewish plots against the Christian community, from well poisoning to child murder. Less expected perhaps is Christian anxiety about Jewish martial activity or kingship.
For Jews to posit the existence of one or more Jewish kingdoms outside Christian dominion undermined one of the fundamental arguments of Christendom against the Jews. "The scepter shall not pass from Judah, nor the law from between his feet until Shiloh comes and the obedience of the peoples belongs to him" (Genesis 49:10); Christians interpreted this verse as a prophesy that Jewish political independence and kingship would end with the coming of the messiah, namely Jesus. In Byzantium, Genesis 49:10 figured prominently in Jewish- Christian polemic. The biblical passage continued to be central in early western Jewish and Christian discussions of Jewish power. However, early medieval western European Christians and Jews approached this question differently than their counterparts in the eastern Mediterranean. Western Jews and Christians debated not merely whether the "scepter of Judah" had passed, but whether a distant eastern Jewish king, whose subjects consisted of one or more of the lost ten tribes of the Jews, might possess it. The focus of Christian consternation and Jewish hope remained around the figure of a Jewish king, that is, the holder of the "scepter." Nevertheless, this king's relationship to the other tribes, and his own tribe of origin became an integral part within these texts.
Before the coming of Islam, Christian authors had a long tradition of depicting Jews and Samaritans as militarily aggressive, treacherous, and hostile to the "Roman" population. The incidents reported from late antiquity were repeated and elaborated upon by medieval Christian writers as well. Instances such as the clash of the Christian monk, Barsauma, who purportedly battled 15,000 armed Jews, or the more historically grounded sixth-century Jewish king of Himyar, Dhu Nuwas, who forced the local Christian population to convert to Judaism before being defeated by Ethiopian forces, became part of eastern Christians' narrative memory of relations with Jews in Byzantium, the Middle East, and Arabia. Similarly, during the Persian capture of Jerusalem in 614 Christian sources describe Jews as aiding the Persians and brutalizing the Christian population. Regardless of the truth or mendacity of these depictions, what is clear is that eastern Mediterranean Christians feared Jewish martial activity. Such anxieties reached apocalyptic proportions during the seventh to ninth centuries in texts such as the Apocalypse of Pseudo-Methodius or the Apocalypse of Daniel, wherein Jews, sometimes specifically under a leader from the tribe of Dan, would gather and persecute Christians at the end of days. Scholars have posited a number of theories about the meaning of Jews in Christian apocalyptic, including the possibility that Jews were rhetorical foils for Muslims within Christian texts, yet all of this literature points to intense anxiety on the part of late antique and early medieval Christians in the eastern Mediterranean about past, current, or future Jewish military activity. Even when Jews were defeated, as they regularly were according to historical and hagiographic sources, the martial potential of Jews continued to cast a shadow of fear on Christians' imagination and became part of Christian cosmology.
Yet it was not merely Christians who reported or imagined Jewish power or ability to act. A poem by the eighth-century Jewish writer R. Elazar ha-Kallir indicates that Jews re-established the Temple cult briefly under the Persians, whereas various versions of three Jewish apocalypses that seem to stem from the early Byzantine-Persian-Muslim conflicts, indicate that this attempt took place under Muslim rule. Byzantine Christian written polemical "dialogues" regularly portray Jews as taunting Christians with their loss of power to the Muslims as a retort to Christian attempts to prove that Jews' loss of sovereignty indicated that they were no longer the chosen people of God. Although one must be cautious about accepting Christian portrayals of Jewish belief, the persistence of this retort attributed to Jews might also be indicative of the frequency with which Jews were willing to evoke this problem to their Christian neighbors in Byzantium.
In western Europe, remarks by Isidore of Seville (560–636) in his De fide catholica contra Judaeos and Julian, Archbishop of Toledo (652–690) in De comprobatione aetatis sextae indicate that already by the seventh century, Latin Christian interpretations of the "scepter of Judah" were disturbed by allegations of distant Jewish kingdoms. Refutations of Jewish power based on Genesis 49:10 abound in both Isidore and Julian's polemic. The amount of space and energy devoted to this point suggests that the two authors found Jewish arguments to the contrary quite unsettling much as the Byzantine Christian authors did. As similar as the Byzantine and early Iberian argumentation is, however, there are some important differences. The repeated attempts on the part of Isidore and Julian to insist that Jesus was the fulfillment of Genesis 49:10 do suggest a certain level of Christian anxiety on the subject in Iberia, like in Byzantium. However, the tone of the Iberian Christian authors is more scornful than fearful. Regardless of the identity of this eastern Jewish king, for which the belief in whom Julian and Isidore mock the Jews, that Jews are portrayed as setting their hopes in this figure deviates considerably from the argumentation surrounding Genesis 49:10 in Byzantine sources. In the Byzantine texts, restoration of Jewish power appeared far more immanent either at the hands of the Persians or Arabs, or the hands of the Jews themselves. Nor could Jews taunt their Christian neighbors with the loss of rule in the seventh-century Visigothic kingdom, for the Muslim invasion had not yet reached so far. Thus, the issue of Jewish religious and political power or lack thereof clearly preoccupied early Iberian Christian and possibly Jewish communities, yet the promise or threat of a Jewish kingdom's continued existence or restoration remained a distant one. On the other hand, the choice of this Jewish king's location, however vague, was an ominous one, for this "king," like the Christians' Antichrist, was in the "east."
Even after the conquest by Muslims of part of the Iberian Peninsula, early western European Christian authors continued to take a mocking tone toward Jewish assertions of a distant Jewish king. Given the known direct contact between authors such as Paul Alvero of Cordoba or Amulo of Lyons, and these authors' demonstrated familiarity with Jewish messianic beliefs, the possibility that their descriptions of Jewish arguments might reflect contemporary Jewish attitudes seems plausible. Like earlier Christian authors, although they refute the argumentation for a Jewish kingdom, the urgency with which they sought to discredit belies their stated conviction that statements about Jewish power in distant lands were mere fables.
In 883 a Jew calling himself Eldad and claiming to be from the tribe of Dan appeared in Kairouan (in present-day Tunisia), telling tales of distant Jewish warriors constantly fighting the kings of Kush (Ethiopia), of the sons of Moses hidden away by a river of stones that flowed on every day of the week except the Sabbath. These Jewish warriors, according to the account, came from four of the tribes who had been dispersed during the Assyrian conquest of the ancient kingdom of Israel. In later recensions, all of the ten lost tribes of Israel came to find their place in the narrative, mostly as fierce warriors fighting a variety of enemies—the Muslims near Mecca, the Persians, and the Ethiopians. In the context of early medieval Christian apprehension about claims of Jewish kingship, and hints that these anxieties were based on actual Jewish assertions, one may well imagine the profound disquiet that Eldad's allegations, or those attributed to him, were designed to inspire among Christians, alongside the hopes of Jews who believed him.