The introduction of Hellenistic Greece started when Alexander the Great conquered the Achaemenid Empire and further regions of Central Asia in 334 BC. Alexander would then venture into Punjab (land of five rivers), which was conquered by Darius the Great before him. Alexander crossed the Indus and Jhelum River when defeating Porus and appointing him as a satrap following the Battle of the Hydaspes. Alexander's army would mutiny and retreat along the Beas River when confronted by the Nanda Empire, thus wouldn't conquer Pubjab entirely.
Alexander founded several cities in his new territories in the areas of the Amu Darya and Bactria, and Greek settlements further extended to the Khyber Pass, Gandhara (see Taxila), and the Punjab. Following Alexander's death on June 10, 323 BC, the Diadochi or "Successors" founded their own kingdoms. General Seleucus set up the Seleucid Empire in Anatolia and Central Asia and extended as far as India.
The Mauryan Empire, founded by Chandragupta Maurya, would first conquer the Nanda Empire. Chandragupta would then defeat the Seleucid Empire during the Seleucid-Mauryan War. This resulted in the transfer of the Macedonian satraps in the Indus Valley and Gandhara to the Mauryan Empire. Furthermore, a marriage alliance was enacted which granted Seleucid's daughter as Chandraguptas wife for diplomatic relations. The conflict additionally led to the transfer of 500 war elephants to the Seleucid Empire from the Mauryan Empire, presumably as expenses of lives lost and damages sustained.
The Mauryan Emperor Ashoka established the largest Indian empire. Following the destructive Kalinga War, Ashoka converted to Buddhism. Abandoning an expansionist adgenda, Ashoka would adopt humanitarian reformation in place. As ascribed in the Edicts of Ashoka, the Emperor spread Dharma as Buddhism throughout his empire. Ashoka claims to have converted many, including the Greek populations within his realm to Buddhism:
Here in the king's domain among the Greeks, the Kambojas, the Nabhakas, the Nabhapamkits, the Bhojas, the Pitinikas, the Andhras and the Palidas, everywhere people are following Beloved-of-the-Gods' instructions in Dharma.