Early history

The Indus plains formed the most populous and richest satrapy of the Persian Achaemenid Empire for almost two centuries, starting from the reign of Darius the Great (522-485 BCE).Its heritage influenced the region e. g. adoption of Aramaic script, which the Achaemenids used for the Persian language; but after the end of Achaemenid rule, other scripts became more popular, such as Kharoṣṭhī (derived from Aramaic) and Greek. The interaction between Hellenistic Greece and Buddhism began when Alexander the Great overthrew the Achaemenid empire in 334 BCE, and marched eastwards. Eventually, after defeating King Porus in the fierce Battle of the Hydaspes (near modern Jhelum), he conquered much of the Punjab region. But, his battle weary troops refused to advance further into India to engage the formidable army of Nanda Dynasty and its vanguard of trampling elephants, new monstorities to the invaders. Therefore, Alexander proceeded southwest along the Indus valley.Along the way, he engaged in several battles with smaller kingdoms before marching his army westward across the Makran desert towards modern Iran. Alexander founded several new Macedonian/Greek settlements in Gandhara and Punjab.
Chandragupta Maurya, who was in this region as a fugitive general from Magadha empire of the Nandas, later raised his own military force and ultimately overthrew the Nanda Dynasty - using Macedonian tactics he had learnt - and founded the Mauryan dynasty in Magadha, that lasted about 180 years.After Alexander's death in 323BCE, his Diadochi (generals) divided the empire, with Seleucus setting up the Seleucid Kingdom, which included the Indus plain.[26] Chandragupta Maurya took advantage of this fragmentation of Greek power and captured the Punjab and Gandhara.[Later, the eastern part of the Seleucid Kingdom broke away to form the Greco-Bactrian Kingdom (third–second century BCE). Chandragupta's grandson, Ashoka the Great, (273-232 BCE) expanded the Mauryan empire to its greatest extent covering most of South Asia. He converted to Buddhism after feeling remorse for his bloody conquest of Kalinga in eastern India. His Edicts were written on pillars in Aramaic (the lingua franca of the Achaemenid Empire) or in Kharoṣṭhī.

Greco-Buddhism (or Græco-Buddhism) was the syncretism between the culture of Classical Greece and Buddhism in the area of modern Afghanistan and Pakistan, between the fourth century BCE and the fifth century CE.It influenced the artistic development of Buddhism, and in particular Mahayana Buddhism, before it spread to central and eastern Asia, from the 1st century CE onward. Demetrius (son of the Greco-Bactrian king Euthydemus) invaded northern India in 180 BCE as far as Pataliputra and established an Indo-Greek kingdom. To the south, the Greeks captured Sindh and nearby coastal areas, completing the invasion by 175 BCE and confining the Sungas to the east. Meanwhile, in Bactria, the usurper Eucratides killed Demetrius in a battle. Although the Indo-Greeks lost part of the Gangetic plain, their kingdom lasted nearly two centuries.

The Indo-Greek Menander I (reigned 155-130 BCE) drove the Greco-Bactrians out of Gandhara and beyond the Hindu Kush, becoming a king shortly after his victory. His territories covered Panjshir and Kapisa in modern Afghanistan and extended to the Punjab region, with many tributaries to the south and east, possibly as far as Mathura. The capital Sagala (modern Sialkot) prospered greatly under Menander's rule and Menander is one of the few Bactrian kings mentioned by Greek authors.The classical Buddhist text Milinda Pañha, praises Menander, saying there was "none equal to Milinda in all India".His empire survived him in a fragmented manner until the last independent Greek king, Strato II, disappeared around 10 CE. Around 125 BCE, the Greco-Bactrian king Heliocles, son of Eucratides, fled from the Yuezhi invasion of Bactria and relocated to Gandhara, pushing the Indo-Greeks east of the Jhelum River. Various petty kings ruled into the early first century CE, until the conquests by the Scythians, Parthians and the Yuezhi, who founded the Kushan dynasty. The last known Indo-Greek ruler was Theodamas, from the Bajaur area of Gandhara, mentioned on a 1st century CE signet ring, bearing the Kharoṣṭhī inscription "Su Theodamasa" ("Su" was the Greek transliteration of the Kushan royal title "Shau" ("Shah" or "King")).

The Indo-Scythians were descended from the Sakas (Scythians) who migrated from southern Siberia to Kashmir and Arachosia from the middle of the 2nd century BCE to the 1st century BCE. They displaced the Indo-Greeks and ruled a kingdom that stretched from Gandhara to Mathura and Scythian tribes spread further into northwest India and the Iranian plateau.

The Parni were a nomadic Central Asian tribe who overthrew the Persian Seleucids and annexed much of the Indus region. Following the decline of the central Parthian authority after clashes with the Roman Empire, a local Parthian leader, Gondophares established the Indo-Parthian Kingdom in the 1st century CE. The kingdom was ruled from Taxila and covered much of modern southeast Afghanistan, Pakistan and northwestern India.

The Kushan kingdom founded by King Heraios, and greatly expanded by his successor, Kujula Kadphises. Kadphises' son, Vima Takto conquered territory now in India, but lost much of the west of the kingdom to the Parthians. The fourth Kushan emperor, Kanishka I, (circa 127 CE) had a winter capital at Purushapura (Peshawar) and a summer capital at Kapisa (Bagram). The kingdom linked the Indian Ocean maritime trade with the commerce of the Silk Road through the Indus valley. At its height, the empire extended from the Aral Sea to northern India, encouraging long-distance trade, particularly between China and Rome. Kanishka convened a great Buddhist council in Kashmir, marking the start of the pantheistic Mahayana Buddhism and its scission with Nikaya Buddhism. The art and culture of Gandhara are the best known expressions of the interaction of Greek and Buddhist cultures, which continued over several centuries until the fifth century CE White Hun invasions. Over the next few centuries, the White Huns, Indo-Parthians, and Kushans shared control of the Indus plain while the Persian Sassanid Empire dominated the south and southwest. The mingling of Indian and Persian cultures in the region gave rise to the Indo-Sassanid culture, which flourished in Balochistan and western Punjab. The Gupta Empire arose in northern India around the second century CE and included much of the lower Indus area as a province. The Gupta era was marked by a local Hindu revival, whose impact was felt in the distant Punjab/Sindh region, although Buddhism continued to flourish and the Gupta empire had little influence on modern day Pakistan.According to Arab chroniclers, the Rai Dynasty of Sindh (c.489-632), established a great kingdom with Ror (modern Sukkur) as its capital and, at its zenith, under Rai Diwaji (Devaditya), ruled over the Sindh region and beyond. Devadittya was a great patron of Buddhism, which flourished. This kingdom was taken over by Brahman dynasties, whose unpopularity among Buddhist subjects contributed towards the consolidation of Arab conquerors' base in Sindh.