David the Black (David Negro / David ben Gedaliah) was one of the most prominent Jewish figures in 14th century Portugal, occupying an exceptional position within the royal administration. He served King D. Fernando I as almoxarife of the customs and as a high-ranking financial officer, a role that placed him at the center of fiscal collection, maritime trade, and the economic circulation of the Tagus estuary. Such a post was extremely rare for a Jew in medieval Portugal and granted him prestige, direct access to the royal court, and the capacity to acquire and manage extensive properties along the southern bank of the river.

Documentary sources indicate that David owned lands, tidal channels, salt-production rights, and productive infrastructures in areas such as Amora, Arrentela, Corroios, and Seixal. These territories were strategically vital for supplying Lisbon with salt, agricultural products, and riverine resources. His involvement in the management of these spaces helps explain both the durability of his memory in the region and the association with local toponymy, notably the Rio Judeu, a branch of the Tagus whose name reflects the sustained activity of Jews and, later, New Christians in the riverside economy.

The political crisis that followed the death of King D. Fernando I in 1383 marked a turning point in David’s life. He supported the claim of D. Beatriz, placing himself in opposition to the faction that would elevate D. João I to the throne. As a consequence, in 1384 his properties were confiscated and granted to the Constable D. Nuno Álvares Pereira. This confiscation effectively erased his material presence from the Portuguese landscape.

Forced into exile, David left Portugal and settled in Toledo, where he continued to appear in documents associated with the Castilian Jewish community. He died there in 1385. His trajectory illustrates the extent to which Jews could be deeply embedded in the political, economic, and territorial structures of late medieval Portugal, particularly along the southern bank of the Tagus, as active agents rather than marginal figures.