Successor governorate to New Andalusia administering the Río de la Plata basin under the Viceroyalty of Peru and (from 1661) the Real Audiencia of Charcas/Buenos Aires; Paraguay was separated into its own governorate in 1617.
Superseded by the newly created Viceroyalty of the Río de la Plata in 1776.
The atlas holds 2 border frames for Governorate of the Río de la Plata — the shape you scrub through changes in 1542 · 1618.
Same Hakluyt Society primary-source volume as the New Andalusia predecessor entity; flagged as partial coverage since it only narrates through 1555, well short of this polity's 1776 end — best polity-specific match found, no fuller single monograph located in Open Library search.