They are referred in Alif Laila wa Laila (1001 nights) as Sindabadis (person of Sindh.) The story takes place in Basra, and it is of one Sindabadi speaking to another Sindabadi of his adventures at sea.
Sindh is one of the most ancient and important regions of the ancient world. Sindhi was world-renowned for its riches and unique culture, seafarers and navigators.
Mohenjo daro
Sindhi culture is a direct derivative of the IVC, and we even have the Priest King statue of Mohenjo daro wearing an ajrak.
This region was also connected to the Umayyad Khalifat in the beginning of the Muslim conquest and the first to embrace Islam in modern day Pakistan.
So Arabs should forget their pre-Islamic past while Prophet Muhammad saws praised the nobility of Arab culture?
Did you know Abu Bakr RA was his historian and had knowledge of the history of all the Arab tribes, hence the Prophet saws took him along on every diplomatic mission.
The same Prophet Muhammad saws who exalted the civilization and knowledge of Persians in warfare which availed the Muslims at Ghazwa Khandaq.
The same Prophet saws who praised the Abyssinians for their spear play and martial prowess, and did not stop their parades and festivities.
Embrace your culture and recognize the beauty which Allah swt has blessed us with. There is no issue as long as you uphold Islam and do not go against it.