See Loreto guide for highlights and historic monuments
Regarding the earliest documents referring to Loreto, we have a 'secure' (ie certain) document from the 12th century, but some scholars suggest other sources from the early eleventh century (from 1018).
On top of Mount Prodo there was a church dedicated to Saint Mary, and in a document of 1193 the church and its assets were donated by Jordan, Bishop of Umana, to the Monastery of Fonte Avellana:
"[...] In the name of God, in the year 1193 from the Incarnation of Our God Jesus Christ ... We always concede to the monastery of Fonte Avellana and you, Marco, venerable Prior ... the Church of Saint Mary of Loreto, which is located in the ‘fundus’ of Loreto ..." .
Loreto was therefore indicated in the documents as being the "fundus (farm) Laureti" and, as explains G. Cappelletti, "that church ... and the parish were called 'Sancta Maria de Laureto' or 'in Laureto'. "
Having established the 11th - 12th century origins of Loreto, a historical problem exists about the level of population in the “fundus”. For some scholars “Lauretum” in the 13th century was already a “vital” village":
“Already in 1194 Loreto is a vital and established village, around which enlarges a wide range on the 'fundus'”) .
For other scholars, however:
“still in the 13th century the site of Loreto does not host any social group: it was simply a 'fundus' in the territory of Recanati” .
Probably, Loreto in the 13th century was a small village and its history really began in the 15th century when it became the site of a sanctuary dedicated to Our Lady, famous throughout Europe.
Origins of the name Loreto
With regard to the etymology of Loreto, it is equally well explained by the same G. Cappelletti, who noticed that, probably, the farm was "covered with laurels" and, for that reason, "in Latin it was said “Lauretum” (“laurel wood”)". Which is true, as demonstrated by recent studies that also report a much earlier date than 1193:
“[..] 'Lauretum' place, planted with laurel trees ... since 1018 was dependent on the Diocese of Senigallia, Fermo and Ancona County; but, since 1179, it was attached to the Diocese of ‘Umana’, which was subject to Recanati [...]" 
See also the travel guide for Loreto.
1. This document is contained in G. Cappelletti, “Le Chiese d'Italia dalla loro origine fino ai giorni nostri” [“The Churches of Italy from their origin to the present day”], 1848, p. 90
2. See “Loreto”, Istituto Italiano d'Arti Grafiche ["Loreto", Italian Institute of Graphic Arts], 1910, p. 28
3. See “Assistenza e ospitalità nella Marca medievale: atti del XXVI Convegno di studi maceratesi”, San Ginesio, 17-18 November 1990
4. See E. Alfieri, 1971, p. 6