The name Kiera has its origins in the ancient Irish Gaelic language, with its roots dating back to the early medieval period. Kiera is a variant spelling of the Irish name Ciara, which is derived from the Gaelic word "ciar" meaning "dark" or "black-haired." This name was initially given to children with dark hair or complexions.

During the Middle Ages, Kiera was a relatively common name among the Irish nobility and aristocracy. It gained popularity as a feminine form of the male name Ciarán, which also stems from the same Gaelic root. The earliest recorded instance of the spelling "Kiera" dates back to the 12th century, found in ancient Irish genealogical records.

One of the earliest notable historical figures with the name Kiera was Kiera Ní Lochlainn, a 14th-century Irish noblewoman and chieftain of the Uí Lochlainn dynasty in County Donegal. She played a significant role in the political affairs of her time and was known for her leadership and strategic acumen.

In the 16th century, Kiera O'Malley (1520-1585) was a renowned Irish harpist and composer who performed for the Tudor court of Queen Elizabeth I. Her musical talents earned her recognition and patronage from the English nobility.

The name Kiera also appears in religious texts and literary works. In the 17th century, the Irish poet and mystic Kiera Ní Dhomhnaill (1620-1692) gained fame for her spiritual and devotional poetry, which reflected the deep Catholic faith prevalent in Ireland at the time.

During the 18th century, Kiera O'Connor (1742-1818) was a prominent Irish revolutionary and patriot who participated in the Irish Rebellion of 1798. She was celebrated for her bravery and commitment to the cause of Irish independence.

In more recent times, the actress Kiera Knightley (born in 1985) has brought renewed popularity to the name Kiera. Her successful career in films such as "Bend It Like Beckham" and the "Pirates of the Caribbean" series has contributed to the name's contemporary appeal.

While the name Kiera has endured through the centuries, its origins can be traced back to the rich cultural heritage of ancient Ireland, where it was deeply rooted in the Gaelic language and traditions.