The letters from the family of Don Diego José Carrillo de Albornoz (1724-1789), V Conde de Montemar, date from 1761 to 1799. This family, descendants of Spanish Conquistadors, was one of the most powerful in the Viceroyalty of Peru and in Spanish nobility. During this time period, the Carrillo de Albornoz siblings held more titles than any other family in Peru. The letters where written by his brother, Don Pedro José Carrillo de Albornoz (d.1799), although there are a few written by the Don Diego and his brother in law Don Francisco Manrique de Lara. In total, there were sixteen siblings in this generation. The close to 280 letters travelled between Lima, residence of Pedro, Trillo, and Madrid, where Don Diego moved as part of belonging to the Spanish Royal Court.
The Conde de Montemar estate, later linked to the heir of the Conde de Monteblanco, grew to probably being the wealthiest of the Viceroyalty, which by the end of the eighteen and beginning of the nineteenth century had surpassed one million pesos. The content of the letters vary in theme and length. Topics range from greetings and family updates of marriage, to professional careers, army and security, vice-royal affairs and politics, trade and commerce, nobility, Indian affairs, the inherited estate of the Ducado (mayorazgo), and others. Several people are mentioned, from their third grandfather’s estate, to noble aunts and cousins, to local priests and bishops. Travel routes and inter viceroyalty itineraries are mentioned.