Afghanistan once lay between two great ancient civilizations, the Indian and the Persian (Iranian) which both influenced the region. For instance, it is believed that the pre-occupation with the veiling of women stems from pre-Islamic Persian practices which had an impact on life in ancient Greece, and later, even Rome.
And Greek interests in the Persian territories, most notably with the incursion by Alexander of Macedon in the 4th century BCE, carried Hellenism right to India's mountainous frontier with Afghanistan.
Cultural ties between Afghanistan and India go back at least to 4500
BCE. There is evidence, in the ruins of the Indus Valley cities that once
flourished by the now-vanished Saraswati River, of cultural and trade relations
between the two regions. Vedic deities such as the Maruts also have links
to Afghanistan. Tribal names of Afghanistan today can be traced to
mentions of the Ten-King or Arya-Dasa conflicts of the Rig Veda that
occurred in Seistan, a province of southern Afghanistan. The purs
destroyed by Indra were mounds formed in the region due to erosion from the Bad-i-sad-o-bist,
ie. the 120-day winds.
Northern Afghanistan lay on the famous Silk Route, and that commercial
activity may have facilitated the spread of Buddhism which led to closer ties
Until the 10th century CE, Hindu kings ruled Afghanistan and later, parts of it. The writings of scholar-historian Al-Biruni (973-1048 CE) say the kings of India continued to have coronations in Kabul even when the city had passed out of their hands.
At its peak in the 1800s, an Indian empire extended from Kabul to Burma (with cultural colonies farther east before then, eg. Indo-nesia.) Even when Afghanistan had become a separate nation, it continued to regard India as "the mother country." ~ S. Londhe's interesting site.
"Northwest Frontier" (Pakistan-India Border region) also has historical links to Tibet
NB. Alexander of Macedon, called The Great, is known in Asia as Iskander. Former aerial surveyor, A. Denis N. Fernandes, a Fellow of the Royal Society, points out that the etymology of Ghandara may, in fact, derive from that version of the Macedonian's name. For more about the Bamiyan figures and similar, but smaller ones known as the Augana, Aukana or Awkana (transliterations of the Persian form of Afghan) Buddhas, in South India. The Bamiyan statue was 180ft. high while those of Sasseruwa and Kalawewa are 39 ft. tall.