Wikipedia
Aljama (, , ) is a term of Arabic origin used in old official documents in Spain and Portugal to designate the self-governing communities of Moors and Jews living under Christian rule in the Iberian Peninsula. In some present-day Spanish cities, the name is still applied to the quarters where such communities lived, though they are many centuries gone.
The Jewish communities of Spain, owing to their social isolation and to the religious and political regulations imposed upon them, had always formed groups apart from the rest of the population. The authority exercised by their own rabbis and the system of tax-collection by the heads of the congregations for the administration of communal affairs, placed them almost completely without the jurisdiction of the government of the country; and, as a result, they soon came to be dealt with by the officials not as subjects amenable to the general law of the land, but as collective bodies with special privileges and special duties.
Thus, the Visigothic kings imposed a tax not upon each individual Jew or upon the heads of families, but upon the community as a whole, allowing the communal authorities to fix the individual rate of taxation. But both under the Visigoths and under the Moors there was neither regularity in the transactions of the rabbis and elders nor system in the attitude of the government toward the Jewish communities. With the reestablishment of Christian rule, however, the relation between the government and its Jewish subjects gradually became a well-defined one.
In 1219 and 1284 in Toledo, in 1273 in Barcelona, in 1290 at Huete, and on more than one occasion during those years in Portugal, councils were held of Spanish officials and Jewish representatives for the purpose of establishing a just rate of taxation for Jewish communities, and of devising adequate means for tax-collection. This first official recognition by the government of the Jewish communities as separate bodies led to a still further change in the treatment of the Jewish congregations and in the legislation, both local and national, regarding them.
The bishops of the various districts assumed immediate authority over them, and, in conjunction with Jewish representatives, formed rules which were henceforth to govern the communities. The elections of rabbis and judges were to be held at stated intervals, and the names of these dignitaries submitted to the bishop for approval; there was to be a Rabino mayor (Rab de la corte; "court rabbi") for the presentation of communal questions before the proper authorities; and the heads of the congregation were made answerable for the conduct of the community. In all government action, whether local or general, the unit considered was in most cases the community, not the individual Jew.
The governing authority of the state sometimes nominated a member of the Jewish community to the administrative position of crown rabbi to act as intermediary between the aljama and the state. For example, in the Kingdom of Aragon King John I issued edicts in 1386 defining the functions and duties of the . There were various requirements as to the good character and faith of the person holding the position, as well as a requirement that he live among the entourage of the Court, and thus away from his community, and in constant contact with the Christian majority population. His powers and authorities over the of Castile, economic, judicial, and otherwise, were specified.