This question might be answered from several perspectives. But, what appears to be the real reason for ignoring this period of history – is the purposeful whitewashing of some watershed moments of India.
These were the time when Islamic invasion had started in India. These invasions were directly coordinated by Islamic Caliphate. Teling history if this period requires teling about attack on Sindh by Muhammad Bin Quasim, That would have raised curiosity about the area , which is today known as pakistan. Some inquisitive minds would have naturally asked – how hindu / budhist area became Muslim majority, that eventially lead to partition ?
When the policymakers had already decided that they would be teaching only tailored history, then we could not expect honesty in historiography . Take for example, the description of genoside by Muhammad Bin Quasim –
“Even the early Arab invaders of India sponsored by the Caliphate were as unapologetic of the slave taking and beheading as the ISIS is. Muhammad bin Qasim who invaded North Western India on the orders of Caliph Walid and his Iraqi General Hazzaz was instructed “to give no quarter to infidels, but to cut their throats, and take the women and children as captives”. He proceeded accordingly. After sacking Debal, he captured “700 beautiful females, who were under the protection of Budh (that is, had taken shelter in the temple), were all captured with their valuable ornaments, and clothes adorned with jewels” and according to the directions of Scriptures dispatched 1/5th of their numbers to his master and the sponsor of Jihadist campaign Hajjaj and distributed the rest among his soldiers. In Rawar, Qasim’s army took 600 people as slaves of which 30 women of royal lineage were sent to Hajjaj who “presented them” to Caliph Walid who “sold some of these captives of royal birth and some he presented to others.
Now, do we realistically expect these events to be told by the marxist historians ?
If one has any doubt about intention of Marxist academecians – let me Quoat Mr. SL Bhyrappa, who was denied the membership in commitee of history writing in 1969–70, because he did not succumb to the pressure of govt. see an excerpt from an article of Mr Bhyrappa himself about what happened in 1969–70
Dr. S L Bhyrappa on Distorting Indian History
What we really need to do is to analyze the present political attitudes in teaching history. In order to do this, let me first present what I learnt of the nature of the prevailing political control through my own experience.
During the year 1969-70 the Central Government under Mrs. Indira Gandhi established a committee under the Chairmanship of G. Parthasarathy, a diplomat close to Nehru-Gandhi family. Its task was to integrate the nation through education. At that time I was a reader in Educational Philosophy at NCERT and was selected as one of the five members of the committee. In our first meeting Mr. Parthasarathy, as Chairman of the committee explained the purpose of our committee in typically diplomatic language: “It is our duty not to sow the seeds of thorns in the minds of the growing children which will grow up as barriers to national integration. Such thorns are found mostly in the history courses. Occasionally we can find them in language and social science courses also. We have to weed them out. We have to include only such thoughts that go towards inculcating the concept of national integration firmly in the minds of our children. This committee carries this great responsibility.”
The other four members were nodding respectfully. But I said, “Sir, I am unable to understand your words. Will you please explain with a few illustrations?” The Chairman responded: “Ghazni Mohammed looted the Somnath Temple, Aurangzeb built mosques by demolishing the temples in Kashi and Mathura, he collected jizya — is it possible to build a strong India under the present circumstances by conveying such useless facts? What purpose do they serve, other than generating hatred?”
“But are they not historical truths?” I persisted.
“Plenty of truths are there. Using these truths judiciously is the wise way to teach history,” he retorted. The remaining four members simply nodded their heads saying, “Yes, yes.” But I was not prepared to let him off.