All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.
This Hadeeth in which the conquest of India is mentioned was reported by An-Nassaa’i, Ahmad, Al-Bayhaqi and others from Thawbaan and Shaykh Al-Albaani classified it as Saheeh in "Saheeh Al-Jaami’".
Besides, Ibn Katheer said in his book "An-Nihaayah Fil-Fitan Wal Malaahim": “Indeed, the Muslims conquered India in 44 (A.H) during the reign of Mu’aawiyah Ibn Abi Sufyaan and some incidents took place and we mentioned them in detail. Also, the great king As-Sa’eed Al-Mahmoud Ibn Subiktikeen, the ruler of Ghaznah and its surroundings conquered it in about 400 (A.H) and he did there some renowned acts and good matters and he broke the great idol called "Somnath" and took its garlands and swords and returned to his country victorious and safe."
Indeed, Nu'aym Ibn Hammaad Al-Marwazi in his book "Al-Fitan wa Ashraat as-Saa’ah", stated a narration that suggests that this will happen before the descent of ‘Eesa (Jesus) ; the narration reads: “People from my nation will conquer India and Allaah will make them victorious to the extent that they will bring the kings of India handcuffed in chains and Allaah will forgive for them their sins and they will withdraw to Ash-Shaam i.e. the Levant (Greater Syria) and they will find ‘Eesa in Ash-Shaam.”
Shaykh Hammoud At-Tiweejri said: “What was mentioned in the Hadeeth that was reported by Nu’aym Ibn Hammaad from Abu Hurayrah about the conquest of India, has not yet taken place, and this will happen when ‘Eesa will descend, if the Hadeeth in this regard is authentic.”
To conclude, the Hadeeth of Thawbaan could refer to what happened at the time of the Companions and the Hadeeth of Abu Hurayrah could refer to what will happen when the Hour draws near, which is at the time when ‘Eesa will descend.
Allaah Knows best.