Comte Humbert's landholdings were gradually expanded by his descendants and united under a single government.The most important step in this process was the marriage of Humbert's son Odon to Adelaida, heiress of the marquisate of Susa, whose territories extended between the Alps and the River Po (including Auriate, Turin, Ivrea and Aosta) and as far as the Mediterranean coast between Ventimiglia and Albenga, and also included control of the Alpine passes of Mont-Cenis and Saint-Bernard.
The book of anniversaries of the church of Aosta includes an entry dated 1040 the dating clause of which notes "regnante et principante in Valle nostra August Salassorum Umberto P. This is the origin favoured by Guichenon after reviewing numerous alternative theories.
In addition to "tradition" in the family, he bases his conclusion on an anachronistic heraldic argument and a supposed common connection with St Maurice.
Comte Amede VIII was created duke of Savoy by Sigmund King of Germany in 1417.
Research into the family of the counts of Savoy is complicated by the loss of original primary source documentation in the 12th, 13th and 14th centuries.
The county of Savoy (Saboia, pagus Savogiensis) was situated in the north-east part of the diocese of Grenoble, although no specific reference has been found in primary sources to counts in this area before the 11th century.
The family of the counts of Savoy first acquired power in the central part of the Burgundian kingdom during the latter part of the reign of King Rudolf III, when the Comtes de Genve and the Comtes d'Albon were also emerging as local power forces in the area.
Comte Pierre II increased the Savoy family's territories by acquiring land in western Switzerland, mainly at the expense of the Comtes de Genve.
Comte Amede V, older surviving son of Comte Thomas II, was chosen to succeed his father, in place of the infant son of his deceased older brother.
He identifies Braud with "Berthold" who is named in two charters of Rudolf III King of Burgundy dated 10 (see the document BURGUNDY KINGDOM NOBILITY).
Guichenon also launches into highly speculative conjecture about the precise origin of Braud in the families of Widukind and Emperor Otto I (set out in the document SAXONY DUKES) which is not worth summarising.
Comte Thomas further expanded the family's territories northwards into Vaud in present-day Switzerland and eastwards to Piemonte in northern Italy. He appears to have been the first member of the family to use the title "Comte de Savoie".