People from Arabia and middle-east, either pre islamic or Islamic, were never concern for India. They invaded for only 100 years in history and were thoroughly defeated by Bhaarat. They are the concern of Persians. 8 invasions before Muhammad bin Qasim were defeated by Sindh for 80 years continuously. After Qasim's conquest, they were repelled from Sindh within few decades by Sumer Rajputs after battle of Rajasthan.
The problem of Central Asia
India's concern has always been central Asia. Even before Islam, central asians have been invading India since the days of Rigveda. In fact, Rigveda gives first account of probable central asian invasion on Bhaaratas in form of DashaRaagna Yuddha (War of Ten Kings). In fact, they are the only ones which were able to defeat Bhaarat partially or completely. Persians and Chinese had no problems with Indian civilization. The greeks which succeeded in venturing into Indian heartland were again Bactrian greeks from Afghanistan, not the original Greeks. Shaka, Kushan, Hun, Mongol, Ghuri, Gaznavi, Mughal, Turks, Durranis, Taliban, all are central asian intruders. The Islam which ventured to Bhaarat successfully was central asian variant of original Islam which was accepted because of its user-friendly nature for tribal societies of medieval world. The tribes of central asia were the common enemies of Bhaarat, Persia and China. In fact they were the only ones which at some point of time in history were able to dominate all three of these ancient civilizations.
The Central Asian mentality
Gaaznavis and Ghuris and other central asian rulers of Delhi Sultanate like Khiljis, Tughlaqs, Lodhis and Suri's, and Mughals invaded and looted Bhaarat and destroyed temples and converted people in the name of religion. But, it is matter of great speculation when it comes to how much Islamic were they, when seen from today's standards set by Taliban and Saudi Arabia about purity of Islam. So many of them were openly homosexuals. Akbar dared to start his own religion and started calling himself Zill-e-Ilaahi (shadow/image of god) thereby associating himself with Allah, which is the most venereal sin in Islam.
Interesting thing about the invaders like Mehmud of Gazni and Muhd Ghuri is that they were very much insiders when talking about contemporary Bhaarat. Until Twenty years before Mehmud of Gazni assumed power, the king of Gazni was Raaja Shiladitya. Now, it is not the case that Kings of Gaandhar did not make war with kings of Kekay and Punjab. They very much did. Just that, as long as the kings on both sides of Khyber were followers of Bhaaratiya traditions, this was strictly a political affair.
After defeat of Huns by Yashodharma in 5th century CE, India (the core and NWFP) enjoyed immunity from central asian invasions for 500 years. Such was the resounding victory of Bhaarat over Hunnic invaders which were powerful enough to overrun the mighty Guptas. In those 500 years, entire southern Afghanistan was brought under Bhaaratiya civilizational sphere thoroughly. This is evident from the fact that Iran was conquered by Arabs completely by 651 AD. Transoxania and upper central asia was conquered and thoroughly Islamized by 709. Sindh was invaded repeatedly for 80 years before Muhammad bin Qasim succeeded. In spite of all this, it took the year of 962 for Alptigin, predecessor of Sebuktigin, to conquer Gazni from Indic king, Shiladitya. And within a twenty years of fall of Gazni, attacks started on Raja Jayapala of NWFP. Afghanistan resisted for 250 years as integral part of Bhaaratiya civilization before being conquered by Islam.
After Islamic conquest, as the rulers of Afghanistan went away from influence of Bhaaratiya civilization, even they started behaving like their central asian hunnic predecessors. Since, Afghanistan was not conquered by Arabs, but by Islamized hordes of transoxania and Iran.
The Road Ahead
Since its creation, Pakistanis have been wanting to move away from their Indian identity and past. They tend to venerate central asian invaders by giving their names to their missiles just because they invaded India. They conveniently forget that these guys (Ghori, Abdali, Gaznavi et al) raped Punjab and their Hindu and Muslim Punjabi ancestors much more than the ancestors of Hindus in Ganges valley. Thus it shows that the "root" of Bhaarat's concern was always the central Asian tribal tendency and horde mentality and not Arabic method of conquest. Pakistan has taken up that mentality and tribal tendency which was always Bhaarat's pain since antiquity.
That mentality with or without Islam, has always been troubling Indians. Just that before Islamization, the problem was comparatively benign; after Islamization of that mentality, it became a malignant problem for Bhaaratiya civilization. That mentality has now migrated from Central Asia into Indian subcontinent in form of Pakistan.
Interestingly, in post independence era, Bhaarat has made a thorough peace with actual heartland of that mentality. Central asia, under Russia's dominance is extremely friendly towards Bhaarat. Afghanistan, was made extremely friendly before civil war and take-over by taliban. Post 9/11, things are again turning in favour of India in Afghanistan. India even has a military base in central asian heartland of Tajikistan.
Thus, it is seen that Bhaaratiya civilization has been eliminating the anti-Bhaaratiya diatribe in Central Asia in past 60 years and have trapped the rabid anti-Indian central asian mentality in Pakistan (Pakistani Punjab, to be precise) from both the sides. Now, in the desperation to fulfil its imbibed central asian traits and instincts, Pakistan will "invade" Bhaarat out of this migrated tendency.
If Bhaarat can withstand that invasion and press it from both the sides, this mentality will fast loose steam and Pakistani people will be forced to rediscover their Bhaaratiyatva (Indicness), just like Shakas, Kushans, Bactrians, Greeks and Huns did.
If Bhaarat fails, that central asian mentality will again enter triumphantly into Indian heartland and fulfil its tryst with the destiny. It is the tryst of Bhaaratiya civilization with this mentality since dawn of civilization. Either of them has to succeed.