The diversity of dialects of the Portuguese language is known since the time of medieval Portuguese-Galician language when it coexisted with the Lusitanian-Mozarabic dialect, spoken in the south of Portugal. The dialectal diversity becomes more evident in the work of Fernão d'Oliveira, in the "Grammatica da Lingoagem Portuguesa", (1536), where he remarks that the people of Portuguese regions of Beira, Alentejo, Estremadura, and Entre Douro e Minho, all speak differently from each other. Also Contador d'Argote (1725) distinguishes three main varieties of dialects: the local dialects, the dialects of time, and of profession (work jargon). Of local dialects he highlights five main dialects: the dialect of Estremadura, of Entre-Douro e Minho, of Beira, of Algarve and of Trás-os-Montes. He also makes reference to the overseas dialects, the rustic dialects, the poetic dialect and that of prose.