An example of this standard analysis, Jayshree Bajoria of the Council on Foreign Relations writes -
Afghanistan holds strategic importance for India as New Delhi seeks friendly allies in the neighborhood, and because it is a gateway to energy-rich Central Asian states such as Turkmenistan and Kazakhstan. "India is looking to ensure that other countries in the region favor or at least are neutral on its conflict with Pakistan," says J Alexander Thier, an expert on Afghanistan at the United States Institute of Peace (USIP). Afghanistan, on the other hand, he says, looks to India as "a potential counterweight in its relationship with Pakistan."And so on. But I shouldn't pick on one random Googled individual - how about an entire special issue of a respected International Politics journal?
There are in fact a number of good reasons why India wants to develop an interest in Central Asia irrespective of a conflict with the Pakistani government - which I believe is, aside from rhetoric, as good as finished for now as Pakistani elites become twisted around India's massive economy.
1. Central Asian energy
India is interested in Central Asian energy but only to prop up the Tajik-dominated Afghan government and deny revenue to the Pashtun, not for Indian energy security purposes.
India's actions may suggest it is interested in natural gas from Turkmenistan. India signed a memorandum of understanding for a pipeline that would pass through the problem Pashtun region of southern Afghanistan and Pakistan (Herat-Kandahar-Quetta). As recently as 2008 India, Pakistan and the Afghan government agreed to buy gas from Turkmenistan.
But while the southern part of Afghanistan where the proposed trans-Afghan pipeline would be laid is the flattest piece of land in the region it is also the most politically unstable. It is not a secure source of energy for India for the long-term, or even for Pakistan or anyone else for that matter. For India, there must be the added consideration that the gas must travel through Pakistan, and Pakistan's own secessionist Baluchistan region.
A state which relies on the trans-Afghan pipeline for its gas could easily become dependent on a high-priced, highly unstable source of energy. Another factor against serious Indian interest are the Indian's own relatively healthy domestic energy supplies. India has large reserves of coal which it currently uses for power generation, newly discovered conventional gas fields, and potential for economic unconventional shale gas, and coal bed methane. So while the Indian government might act interested in Central Asian gas it does not seem to be an essential resource for India.
The pipleline is still important to India in one way: through transit rights. There is $300 million per year up for grabs for whichever Afghan government can control the flow of gas from Turkmenistan. If the Pashtun south controlled the revenue from the pipeline from Kandahar rather than the Tajiks from Kabul the money would prop-up a Taliban type Pashtun regime that does not have strong relations with India, rather than a regime friendly to Tajikistan and India.
2. Strong relations with Tajikistan
Tajiks are culturally closer to Indians than the rural, feuding Afghan Pashtuns. Tajik-Afghanis are urban, business orientated, educated in Indian universities. Tajiks enjoy Indian culture, like Bollywood films and Indian television programmes. Afghan-Indian relations are therefore a euphemism for Indian-Tajik relations as the Tajik community might be expected to gain the most out of the reconstruction projects.
India wants to improve its relations with Tajikistan to use it as a geopolitical stepping stone to out-flank China on its Xingjiang province border. To do this India needs to assist the large Tajik population in northern Afghanistan. India therefore has more interest developing good relations with Tajikistan than with Turkmenistan, and India would also rather be friends with the Tajik population of north Afghanistan than the Pashtun south of Afghanistan. This should be reflected in major aid projects to the region.
Indeed it is. We learn from the first source India has given a $17 million grant to Tajikstan so they can modernise a hydroelectric power plant. We also know India has given $1.2bn in reconstruction aid to Afghanistan since 2001. The largest projects, like the Zaranj-Delaram road connection to Iran, and Salma Dam project near Herat, are all close to sizeable Tajik populations in the Afghan north-west (dark green in the Stratfor map below).
The road project to Iran (from Herat through Nimruz province) is significant because it offers the more urban Tajiks and Uzbeks another trade route with India and the rest of the world through Iran, rather than Pakistan. The road also brings the sea port to closer for the Herat region than the alternative via the Khyber Pass. Additionally the BBC article says India are "erecting power transmission lines in the north" which has returned 24 hour electricity to Kabul.
3. Trade economies
It makes sense for the populous Indian north west (14 million in New Delhi alone) to develop a better trade relationship with Afghanistan - the Tajik north at least. New Delhi is closer to Kabul by road (about 1200km) and air than are Calcutta or Mumbai. A whole swathe of Central Asia including Tajikistan is nearer to the Indian capital than the southern Indian region of Kerela and the city of Chennai. It makes economic sense for the region to become more integrated, such as in the supply of refrigerated fresh fruit and vegetables, and there will always be elites willing to support such moves in return for a slice of the pie.
4. Out-flanking China
In 1962, 48 years ago, India and China fought a war over their border. This conflict is much forgotten - what with the India-Pakistan Kashmir dispute - but is a much more important motivator for India seeking a special-relationship with Tajiks in Central Asia than conflict with Pakistan. India also had a major skirmish with China in 1987 in the Indian north-east. Given India's military superiority over Pakistan it is unlikely to lose a war against Pakistan any time soon but it could against China. This makes India's recurrent conflict with China more significant than its conflict with Pakistan.
The 1962 war is interesting for being a purely land war, fought at high-altitude in the Indian north-west, and being one which India lost. The war of 1962 was fought primarily over the Aksai Chin Himilayas and the Chinese construction of National Highway 219, a militarily strategic road which connected the two troublesome Western provinces, Tibet and Xingjiang.
While India lost the war for Aksai Chin it still considers this territory part of India. Were India in a position of strength and China one of weakness, Indians might attempt to take it back with force - and prop up anti-Han Chinese independent states in Xingjiang and Tibet. However India might be looking to threaten China even before conflict by providing covert assistance to anti-Han Chinese groups via Tajikistan and the road link into Xingjiang across the border in southern Kyrgyzstan (screen cap from Google maps below).
At the elite/government level the Pakistan-Indian conflict is much less immediately important than the Sino-Indian conflict. I expect the trade route between Afghanistan and India to be kept open for now. No, I don't expect Pakistan to be an irrelevance as China will eventually lean on Pakistan, and groups in the region, to undermine Indian interests in Central Asia. This could lead to separation of the undeveloped Pashtun part of Afghanistan from the better functioning Tajik-dominated part and the closure of the Kabul-Wagah trade route.
Received wisdom of the Afghan conflict as a geopolitical tussle between Pakistan and India is therefore not only light-weight, it is wrong as it does not explain current economic cooperation between the two governments (such as the Kabul-Wagah trade route... for now). It also says nothing about India's funding of reconstruction projects which favour Tajik-Afghans. If the Indian interest in Afghanistan was really against Pakistan rather than China there would be more Indian attempts to draw the Pashtuns away from Pakistan. That there do not seem to be such an interest shows the Pakistan-India dispute is less relevant than the India-China one for the continuing Afghan conflict.