The Mughal Empire ruled over the majority of the Indian subcontinent, but were there every any ambitions of conquest or colonization in Indochina or anywhere farther west?
Absolutely, for both Central Asia to the west and Southeast Asia to the east.
The Mughals were Timurids and identified as such, and the Timurid heartland had of course been in Tūrān, what is now called Central Asia. Remember, Bābur himself began his career as the ruler of Fergana, in Central Asia, before being essentially expelled to Kabul, another Central Asian city, and conquering India from there. The Mughals thus had a strong ideological motivation to conquer parts of Central Asia.
The Mughals also saw themselves as a Persianate empire, and influence over the ancient Persianate lands of Central Asia was crucial for recognition by their Persianate peers, the Safavids in Iran and the Uzbeks in Central Asia. The Mughals were particularly concerned about their prestige with respect to the Uzbek khans who now ruled the Timurid homeland; the Uzbek lineage was arguably more glorious than the Timurid because the khans were descended from the great Genghis Khan down the male line,^1 while the Mughals were mere matrilineal descendants of Genghis. The Mughal emperors must also have felt pressured to live up to the Safavids, who ruled the great cities of Iran itself and who had supported the first Mughal emperors in their quest for India.
Besides imperial ideology, Central Asia was important as a source of warhorses. India has few good grazing areas and the imperial Mughal army imported the majority of their steeds, both the small and nimble horses from Iran and the bigger, sturdier ones bred by Turkic nomads. Tens of thousands of horses were annually imported from Central Asia, and a loss of Mughal influence in the area could very well imperil this trade – and imperil the entire Mughal army itself, which was heavily cavalry-focused.
The peoples of Central Asia also tended to have better military capacities than Indians, as the Mughals themselves would know only too well; they themselves had come from the mountains of Afghanistan to take over the Delhi sultanate, which had already been crippled a century earlier by yet another great Central Asian conqueror, the Mughals' very own ancestor Timur. And the Delhi sultanate itself, and its Muslim antecedents, had been founded by Turkic Muslims who entered India from Central Asia.
For all these reasons, the Mughals always had an interest in Central Asia. Yet the icy climate and craggy terrain was extremely hard on the Mughal troops, and while the rhetoric of western reconquest was expressed by all six of the Mughal emperors during the empire's height,^2 only Shah Jahan (r. 1628-1658) of Taj Mahal fame really attempted a major campaign there.
Shah Jahan was already showing interest in a reconquest of Central Asia as early as 1640, when a letter by the Safavid governor of Herat in modern Afghanistan suggests that the Mughal emperor had expressed a desire to "set out for Turkistan" as to reclaim the Timurid "hereditary dominions" and the "cemetery of [their] great ancestors" and to "destroy the foundations of Uzbek opposition." The Mughal chronicle the Shah Jahan-nama similarly claims that:
From the time of the last Emperor Jahangir's death [and Shah Jahan's succession]... the mighty soul of the world-subduing monarch [i.e. Shah Jahan] had been bent upon the [Central Asian] countries of Balkh and Badakhshan, which were properly his hereditary dominions.
To this end, Shah Jahan visited Kabul almost every year from 1639, preparing for what was to be a glorious reconquista. The actual campaign began in 1645 when Nazr Muhammad, the Uzbek khan, was ousted by his son 'Abd al-Aziz. Nazr Muhammad abandoned the Uzbek capital of Bukhara and fled to the eastern city of Balkh, appealing to the Mughals to restore him to the throne.
In February 1646, Shah Jahan's son Murad Bakhsh marched west with 60,000 troops. They crossed the Hindu Kush, the mountain range that divides India from Central Asia, by a succession of mountain passes, each of them thousands of meters high. This was an impressive logistical feat by all accounts, made even more stunning by the fact that this corner of Central Asia was far poorer than the Indian countryside that most of the troops were acquainted with. Enormous caravans stocked with cash and supplies had to be carted over the mountains to support the troops.
The Mughal army reached Balkh by mid-June. Nazr Muhammad delayed the arrival of Murad Bakhsh for as long as he could, then fled to the Safavid empire when the Mughals entered. Central Asian sources claim (and it seems fairly likely) that Murad Bakhsh had had secret orders to capture the khan and present him to Shah Jahan, and that Nazr Muhammad fled when a Mughal general warned him beforehand.
An awkward situation prevailed for the rest of 1646, with the city of Balkh and the neighboring countryside in Mughal hands, its former ruler an exile in Iran, and 'Abd al-Aziz in Bukhara.
Soon after conquering Iran, Murad Bakhsh asked to resign his command. He was sick of the country, Nazr Muhammad's supposed fortune was not actually very large, and the tax revenue to be extracted from the area was a mere fraction of the average Indian province. Shah Jahan initially rebuffed his son, pointing out that Balkh was the "key to the conquest of Tūrān," but the prince eventually left anyways.
The Mughal army remained in Balkh in the winter of 1646-1647, when conditions grew progressively worse. 'Abd al-Aziz, Khan of Bukhara, unleashed armies of nomad Uzbeks upon the countryside who destroyed the grain supplies around Balkh, devastating the (already limited) Mughal capacity to forage for food. Most skirmishes between the Uzbeks and the Mughals were won by the Mughals through their superior artillery, but the Mughal command could never present a coherent strategy to deal with the raids of the far more mobile Uzbeks on horseback. Famine came to the troops in Balkh, made worse by the Uzbek capture of a Mughal supply caravan of thirty thousand oxen and a waterborne epidemic caused by the Uzbeks' fouling of the upper Balkh River. Meanwhile, the winter was so cold – at least for the Indian troops – that "men burned themselves in fires they lit for warmth, and no one left their house for fear of being frozen."
In February 1647, Shah Jahan sent his famous son Prince Aurangzeb to Balkh with a much-needed army and money for the troops. He arrived in the Central Asian city after defeating 'Abd al-Aziz's Uzbek cavalry in a few set-piece battles in the Hindu Kush, but he was still incapable of ending the raids. Meanwhile, 'Abd al-Aziz had so devastated the Balkh region that by 1647, the revenue the Mughals could raise from the area had dropped to one-quarter of its 1645 level. Aurangzeb ultimately asked that he be reassigned to India, "where not only fame, but fortune might be gained." Shah Jahan acquiesced and ordered Balkh returned to Nazr Muhammad, who had in the meantime come home from Iran.
The Mughal army came home in the autumn of 1647. Shah Jahan initially ordered that Nazr Muhammad should personally offer his submission before Prince Aurangzeb as a Mughal vassal. As in 1645, though, the khan delayed his meeting with Aurangzeb to no end. Aurangzeb eventually gave up and his army crossed the Hindu Kush back to Kabul in autumn, harassed by nomad troops all along the way. Once the Mughals left, Nazr Muhammad reentered Balkh bloodlessly. But the Mughal presence and the Uzbek raids had so devastated Balkh that the khan had to beg for money from Shah Jahan for the next few years.
The campaign cost Shah Jahan at least twenty million rupees, possibly as many as forty million, all this for an area whose annual land revenue did not approach two million rupees, and there was absolutely nothing to show for it.
The fate of the 1646-1647 Balkh campaign shows, in microcosm, the reasons the Mughal empire failed to expand significantly beyond the Hindu Kush. The imperial Mughal army was a professional one, whose operations depended on the productive economy of the Indian Subcontinent with its merchants, bankers, and supply caravans. Such an army was ill-equipped to fight a war in Central Asia, where the economic base of the country was far weaker and the lumbering Mughal army was hard-pressed for supplies. 'Abd al-Aziz's Uzbeks had worse weapons than the Mughals and never won a major battle, but in 1647 he still ruled Bukhara and the Mughals abandoned Balkh – because his Uzbek nomads possessed mobility and the capacity to live fully off the land and the Mughals did not, and those were what mattered above all else in seventeenth-century Central Asian warfare.
Padshahnama: Vol. II, pp. 449-709
The Shah Jahan Nama of Inayat Khan (tr. Begley and Desai, 1990), pp. 329-403
Mughal Warfare: Indian Frontiers and High Roads to Empire, 1500-1700 (Gommans, 2002), pp. 111-121, 179-187
"The Mughal Occupation of Balkh, 1646-1647" (Foltz, 1996)
(Continued for Southeast Asia)
^1 The Shaybanids, who ruled the Uzbeks throughout the sixteenth century, were descended from Shiban, the fifth son of Jochi, Genghis's eldest son. The Ashtakhanids, who succeeded the Shaybanids and ruled into the mid-eighteenth century, were descendants of Toqa Temür, Jochi's thirteenth son.
^2 The Akbarnama claims that the Mughal emperor Akbar (r. 1556-1605) ignored the emissaries of the Uzbek ruler Abdullah Khan II at least once because he "had thoughts of reconquering his ancestral territories" (The Akbarnama Of Abul Fazl Vol. 3, Beveridge 1907, pp. 211). Similarly, the Tuzuk-i Jahangiri, memoirs of Mughal emperor Jahangir (r. 1605-1627), states that "I had made up my exalted mind to the conquest of Māwarāʼ an-Nahr (Transoxiana), which was the hereditary kingdom of my ancestors" (The Tuzuk-i-Jahangiri; or, Memoirs of Jahangir, Rogers 1914, pp. 89).