Praise be to Allah, and peace and blessings be upon the Messenger of Allah.
Several narrations have been reported concerning the conquest of India. The most authentic of them is the hadith of Thawban, may Allah be pleased with him, in which the Prophet ﷺ said:
“There are two groups from my Ummah whom Allah will protect from the Fire: a group that will fight in India, and a group that will be with Jesus son of Mary.”
It was narrated by al-Nasa'i and Ahmad. The hadith was graded Hasan by the researchers of Musnad Ahmad, and al-Albani authenticated it in Al-Silsilah Al-Sahihah. The meaning of “protected them” is that Allah will safeguard them from the Fire.
As for the narrations reported from Abu Hurayrah, may Allah be pleased with him, including the statement: “The Messenger of Allah ﷺ promised us the conquest of India...”, they have been transmitted through several chains, but they are not free from weakness:
The chain through Jabr ibn Ubaydah, who is of unknown status, and therefore scholars considered this chain weak.
The chain through al-Bara' ibn Abdullah al-Ghanawi, from al-Hasan al-Basri, from Abu Hurayrah. Al-Bara' is weak, in addition to the fact that al-Hasan's narration from Abu Hurayrah is disconnected.
The chain through Hashim ibn Sa'id, from Kinanah ibn Nabih, from Abu Hurayrah. Hashim ibn Sa'id was considered weak by hadith critics.
Another narration through Safwan ibn Amr, from some unnamed shaykhs, from Abu Hurayrah. It contains an unidentified narrator, and Baqiyyah ibn al-Walid narrated it with 'an'anah, while he was known to practice tadlis.
There is also a narration with wording similar to: “A group from my Ummah will fight in India...”, but it is weak. Its chain contains the 'an'anah of al-Walid ibn Muslim, along with indications that the narration is mursal.
Therefore, the hadith of Thawban is the established and authentic narration concerning the conquest of India, whereas the narrations from Abu Hurayrah in this matter are generally weak in their chains. Thus, details contained in them should not be asserted with certainty unless supported by an authentic proof.
Ibn Kathir mentioned that Muslims invaded the lands of India during the reign of Mu'awiyah, may Allah be pleased with him. Other campaigns in India also took place in later periods, including the campaigns of Mahmud ibn Sabuktigin.
However, the apparent meaning of the hadith of Thawban, together with some of the narrations from Abu Hurayrah if they are authenticated, indicates that the campaign mentioned in these hadiths may be a campaign that will occur in the end times, shortly before the descent of Jesus, peace be upon him, or around his time. The historical campaigns in India are not necessarily the campaign intended by this promise.
Some scholars have stated that the conquest of India referred to in these narrations has not yet occurred and will take place around the descent of Jesus, peace be upon him. However, this determination is based on the apparent meaning of the narrations and is not a definitive textual statement.
Accordingly, it is not correct to say that every historical conquest of India was the conquest mentioned in the hadith. Nor is it correct to assert future details for which there is no authentic textual evidence.
And Allah, the Exalted, knows best.