The title was presumably created (no records of its earlier existence or grants) by King John IV of Portugal, the new monarch, first of the Braganza dynasty, sometime in the 1640s.
The title had no original connection to being one for next heirs of the throne - King John IV had a second son, and soon a third, but the daughter kept Beira and the boys received dukedoms (Braganza and Beja).
The title's first connection with the position of the heir was from 1669 onwards, when it was held by the Infanta Isabel Luísa, Princess of Beira (1669–90), the only then living child of King Peter II.
Then, on December 17, 1734 the title was created anew by King John V of Portugal, in favour of his newborn eldest granddaughter Infanta Maria Francisca.
As the future Joseph I (the then Prince of Brazil) was to remain without sons, the new Princess of Beira would later become the proclaimed heiress and ultimately to ascend the throne.
In 1750 the newly ascended King Joseph I (believing that no sons would be forthcoming--indeed, his wife and he produced no further issue after 1746, as is known in hindsight) proclaimed his eldest daughter the official heiress and granted her the "crown-princely" title Princess of Brazil (but apparently not that Duke of Braganza).
According to the first tradition, the next holder of Beira would be Infanta Mariana Vitória of Portugal (1768–88), the eldest daughter of Maria I and Pedro III.
The others going having died, the eldest son, Infante Pedro Carlos of Spain and Portugal (1786–1812) married his Portuguese cousin Teresa, Princess of Beira, and left issue (see below).
Teresa's only child was her son with Pedro Carlos, Infante Don Sebastian of Spain and Portugal(1811–75), from whom the Dukes of Marchena, Durcal, Ansola and Hernani descend.