Pashto belongs to the North-Eastern group within the Iranian branch of Indo-European languages. Pashto has long been recognised as the most important language of the North-West Frontier Province between Pakistan and India. The Pashto language is believed to have originated in the Kandahar/Helmand areas of Afghanistan. Dari often dominates over Afghan/Pashto in Afghanistan in everyday government use since the capital was moved to Kabul from Kandahar in the 18th century. Pashto was declared by royal decree in 1936 to be the national language of Afghanistan instead of Dari Persian, however today they both share this status and are still widely spoken across present day Afghanistan with most Afghanis being proficient in both languages. The areas of Afghanistan to which Pashto is native are those in the East, South, and South-West bordering on Pakistan. Indeed many inhabitants of the areas on the Pakistani side of the border with Afghanistan belong to the Pashtun ethnic group and are speakers of Pashto. In fact the name of the language, Pashto, also denotes the strong code of customs, morals and manners of the Pashtun people.
The Pashto lexicon is fascinating as it contains side-by-side words going back to the dawn of Iranian, neologisms of all ages and loanwords from several languages acquired over two thousand years. The oldest of these loan words date from the Greek occupation of Bactria in the Third century BC. No special trace of a Zoroastrian or a Buddhist past remains, but the Islamic period has brought a great number of Arabic and Persian cultural words. Throughout the centuries everyday words also have been borrowed from Persian in the West and from Indo-Aryan neighbours in the East. The greater part of the basic vocabulary is nevertheless inherited from Eastern Iranian.
The earliest authenticated records of Pashto as a literary language date from the late sixteenth century, at a time when the whole area was part of the Mogul empire. The language has always been written in the Perso-Arabic script with the addition of certain modified letters to represent the peculiar consonant phonemes of Pashto. In the earliest manuscripts there is a considerable variety in the representation of three consonants, but later a standard system emerged. Since the adoption of Pashto as a national language in Afghanistan, a number of innovations have been introduced into the script which have aided clarity.