Treaty of Saragossa

The Treaty of Saragossa enters the story as evidence of a European claim to Japan: John Blackthorne explains that a papal agreement had assigned Portugal exclusive rights to exploit Japan and other territories, ostensibly in return for spreading Catholicism. Translated by Toda Mariko to Toranaga, the claim transforms an abstract line on a map into a challenge to Japan’s independence, though the scene establishes neither that the claim is binding nor that it can be verified.

Place in the Papal Divisions

Blackthorne places the treaty within a sequence of papal decisions. He says Pope Alexander VI set an initial line of demarcation in 1493; Pope Julius II sanctioned changes to the Treaty of Tordesillas, signed by Spain and Portugal in 1494, in 1506; and Pope Clement VII sanctioned the Treaty of Saragossa in 1529. Blackthorne describes the latter as drawing a second line of longitude through the southern tip of Japan. The treaty’s significance in his account rests on that line’s claimed consequence: Portugal received the exclusive right to exploit Japan and lands extending from Japan and Cathay to Africa, in exchange for spreading Catholicism.

Blackthorne’s Explanation

Blackthorne presents the division as a legal and religious arrangement, not merely a geographical boundary. He argues that when the papal decisions were made, the countries in question—including his own—were Catholic, and that the decisions would therefore bind all nations. He also says Spain and Portugal continue to quarrel over ownership because of the wealth of their trade with Cathay. His account draws on knowledge taught to him by Alban Caradoc and on information from Friar Domingo about Japanese pride and ways of thinking; he traces the treaty’s boundary in the sand as he explains it to Toranaga.

Mariko’s Doubt and the Unresolved Claim

Toda Mariko is visibly disturbed as she translates. She privately questions how the Pope could give Japan to the Portuguese and considers the possibility that Blackthorne is lying, even as she reports that he swears by his faith. Toranaga asks Kiri for her judgment. Kiri believes Blackthorne is telling the truth, but immediately identifies the problem that remains: there is no clear way to prove it, or even part of it. The treaty therefore functions in the scene both as a reported instrument of foreign entitlement and as a disputed claim whose authority over Japan has not been established.