Local population never caused a problem before Bin Qasim. As I said the wars were something like Mahabharata war. Start with sunrise and down with sunset. After sunset you could meet the enemy over tea. It would be in open maidan so that normal life and villagers are not troubled. No civilian property or life destruction. That was dharma yuddha within bounds of moral law. When the islamists came, India had no answer because they spread like locusts killing and destroying everything in their way. How many places and how many lives could kshatriya save. They had no concept of such enemy or war. The non-combatant civilians could not raise arms to protect themselves because they were forbidden by varna system to pick up arms.
White washing history is what the liberals did to our history. The cleaned up all the Muslim atrocities to show how the Muslims did us a favor by killing us. How Hindus were evil caste practitioners and so deserved to be killed. How Hindus were cruel and only storing wealth in temples and hence deserved to be looted. That is called as white washing.
Ashoka had a war in a battlefield where the killed were Kshatriya. Not civilians.
I am surprised that your view of history is so distorted and super-sanitized. Your view is very idealized and is a screen for caste system. So, Kashatriyas were not human? They were bred to kill and be killed. What is moral about that? It is no wonder that there was no larger sense of nationhood. Why would there be? If defending one's homeland is not an issue, then why wonder about India not having an entrenched sense of nationhood?
Ashoka's words are part of history. He clearly talked of his distress at loss of life and brutality that is inevitable result of conquering and subjugating a population. How was that dharma Yudha? If it was a 'routine' matter of killing Kashatriays, whose moral duty entailed killing and be killed, why would Ashoka be distressed? This is what ideology does to history.
The problem started with Bin Qasim, because you are taught that. Problem did not start with Greeks, or Kushans, or Huns. It started with Muslims (not Arabs - because your narrative fails to distinguish because of convenience), because Muslims are still around. Does it matter to you that Alexander was opposed by whole tribes throughout Punjab? No mention of Kashatriyas there. He had so much trouble passing through this area that his army lost heart a number of times. Conquering armies face difficulties only when a population rises to resist an invader, not when an exhaustible supply of trained men is brought to the field in a Dharmic war (as you say).
I read Mr.S.Singh saying something about Bin Qasim's army being powerful. You too brought it up. The simple fact is that wherever Muslim / Arab armies went in that era, they found divided nations and disgruntled populations. Al-Sham (Syria + Palestine + Lebanon), Iraq, Persia, Khurasan (Balochistan + Afghanistan), Central Asia, parts of Asia Minor, Armenia and beyond, Egypt, North Africa, Spain were easily conquered because the empires and kingdoms were fatigued and often (as in Spain) torn with internal dissensions. That is why far less numerous armies of motivated men were able to conquer bigger armies of disaffected people. It was quite similar in Sindh too. There was tension in Sindh between local Hindus and local Buddhists. Plus Raja Dahir does not seem to have enjoyed much support of his people. BTW, to console you and further damage your thesis, let me tell you that Umayyads quickly lost interest in Sindh after the young Bin Qasim was recalled. There was not enough revenue raised in Sindh to be worth the trouble. After a few generations, Sindh and South Punjab again had local Hindu rulers. Muslims and heretical sects (Qarmatians) kept exchanging ruler-ship with Hindus. Turks showed up a couple of hundred years later and we have a better historical sources for Turks than for Arabs. With Turks too similar scenario played out. Beyond the Kingdom of Lahore there was hardly any resistance because of dissensions and petty Rajput kingdoms fighting one another.
Superior organization, better training, better tactics, better equipment, and motivation wins the day. All else is just excuses. Nature does not tolerate weakness. What happens, does so because of Will greater than our understanding. Therefore, I have no quarrel with history. I hope you quit painting history Saffron. History is history, not fiction or art.
If varna system was a reason for failure to repel invaders, then why was it not reformed or discarded even? Failure to adapt means failure to survive. Look around yourself. Where do you see the varna system? Enslaving native genius to abhorrent caste system produced unfavorable results. Why then pine for an age that failed to survive in face of competition? Between Mahmud of Gahzni and Muhammad of Ghur there was a period of more than a century for Rajput kingdoms to reform in order to face the challenge of Turk invasions. Rajputs failed. Instead of quarreling among themselves, they could have made a strategy, pushed reforms of varna system in order to raise more men, and rallied the bulk of countrymen in order to face the challenge. They did nothing and paid the price. Turks faced little or no resistance, unlike Greeks - mainly because of varna system.
You can not make a 'Dharmic' argument here. It does not work in face of reality. You can not call the Arabs and Turks as barbaric invaders either to find a moral space, since they operated large empires, ran effective administrations, raised well-trained armies staffed by capable and educated officers. They succeeded, Rajputs failed. Rajputs were set up for failure. They failed to respond to challenges effectively and could not protect their people - which is the first and foremost duty of a ruler.
Any study of the reasons for success of Muslims (Arabs, Turks) against Rajputs would be revealing. But you would have motivation to ignore this. You might also ignore trying to find reasons why Sultanate of Delhi was able to preserve itself. Would it matter to you that Sultanate of Delhi was able to stop Mongol invasions by a combination of effective diplomacy backed by military power? Can you imagine how many lives were spared as a result? I would like to go on and talk about failure of Sultanate of Delhi in stopping Taimur's army, but my post is already too long.
So yes, Muslim rule was disadvantageous for some sections of Hindu population, but it persevered. You can not argue against success. Muslims were successful rulers and kept their rule because population largely tolerated them. Urban Hindus prospered and provided strength and support to their Kings. There is no white washing here. These are facts. You can not argue against facts.
Fascism died in 20th century, and therefore so did colonialism. We are in a different age. Why should our civilizational attitudes not change as well? Is it important to be a hostage to a motivated and biased version of history? That time is gone. Because it had to go. It had outlived its usefulness. By mixing culture, religion, history, and carrying a sense of victimhood what do Hindutvavadis hope to accomplish? Your gripes and fears are like self-fulfilling prophecies. You go on and be afraid of Muslims and Christians, and you will end up destabilizing India and dig your collective grave - so to speak.