King Wuling of Zhao, probably the son of Zhao Suhou, ascends to the throne at 325 BCE, about halfway into the Warring Kingdoms Era (Chinese historians refer to this as the period between 481 BCE and 221 BCE).

During the early years of his reign the Kingdom of Zhao is constantly harassed by the Eastern Hu, the Linhu, the Liufan, and the Xiongnu, all wandering tribes.

Up to this time Zhao commanders riding on horseback still wore robes and normal court attire, whereas the Hu uniform of pants, belt, boots, fur caps, and fur clothes is much better adopted to fighting on horseback.

Wuling’s reign is to be famous for a single important event: the reforms consisting of "Wearing Barbarian Uniform and the Use of Cavalry in Battle".

Returning from India by land, Alexander is at length rejoined at the Amanis by Nearchus and the fleet, which also has suffered losses.

Alexander's march through Gedrosia proves disastrous; waterless desert and shortage of food and fuel causes great suffering, and many, especially women and children, perish in a sudden monsoon flood while encamped in a wadi.

Philip is assassinated by some of the mercenary troops under his command after the departure of Alexander from India.

Alexander names Eudamus and Taxilas as replacement rulers of Philip's territories.

Alexander, encamped along the Hydaspes, has Indian shipwrights build a fleet of eight hundred to one thousand ships, some as large as three hundred tons, to take the army through Persian Gulf waters to Babylon.

Plutarch reports that Alexander met with Chandragupta Maurya, a low-caste protégé of the Brahmin Kautilya (or Chanakya), probably around Takshila in the northwest, and that he viewed the ruling Nanda Empire in a negative light (classical Greek and Latin sources refer to Chandragupta by the names "Sandracottos" or "Andracottus": "Androcottus, when he was a stripling, saw Alexander himself, and we are told that he often said in later times that Alexander narrowly missed making himself master of the country, since its king was hated and despised on account of his baseness and low birth."

Chandragupta, who will soon overthrow the last Nanda king and found the Maurya Empire, will succeed in bringing together most of the Indian subcontinent.

As a result, Chandragupta is considered the first unifier of India and the first genuine emperor of India.

Ptolemy has been closely associated with Alexander during the advance through the Persian highland; as a result of the former’s successful military performance on the way from Bactria to the Indus River, he receives command (as trierarchos) of the Macedonian fleet on the Hydaspes.

Leaving Porus, …

…Alexander now proceeds down the river and into the Indus, with half his forces on shipboard and half marching in three columns down the two banks.

The fleet's co-commander is Nearchus, a Cretan with naval experience who Alexander in 333 had made satrap of the newly conquered Lycia and Pamphylia, and Alexander's own captain is Onesicritus (both will later write accounts of the campaign).

Alexander subdues Multan, the chief seat of the Malli, but the southward march is attended with much fighting and heavy, pitiless slaughter; at the storming of one town of the Malli near the Hydraotes (Ravi) River, Alexander receives a severe wound—an arrow seems to have entered his lung—that leaves him weakened.

Alexander builds a harbor and docks on reaching Patala, located at the head of the Indus delta and explores both arms of the Indus, which probably at this time run into the Rann of Kutch.

He plans to lead part of his forces back by land, while the rest in perhaps one hundred to one hundred and fifty ships under the command of Nearchus make a voyage of exploration along the Persian Gulf.

Local opposition leads Nearchus to set sail in September 325, and he is held up for three weeks until he can pick up the northeast monsoon in late October.

The first known reference to sugar cane appears in writings by Nearchus, who writes of Indian reeds "that produce honey, although there are no bees".

Alexander too had set out in September along the coast through Gedrosia (modern Baluchistan), but …

…he is soon compelled by mountainous country to turn inland, thus failing in his project to establish food depots for the fleet.

Craterus, a high-ranking officer who had played a key role in the Battle of the Hydaspes, already had been sent off with the baggage and siege train, the elephants, and the sick and wounded, together with three battalions of the phalanx, by way of the Mulla Pass, Quetta, and …

…Kandahar into the Helmand Valley; from there he is to march through Drangiana to rejoin the main army on the Amanis (modern Minab) River in Carmania.