The claim that Mongols worship Lord Shiva is not entirely accurate. The Mongols are a nomadic people who have a rich cultural and religious heritage that is rooted in shamanism and ancestor worship. While there have been historical interactions between Mongols and Hindus, particularly during the Mughal Empire in India, there is no evidence to suggest that the Mongols as a whole worship Lord Shiva.
It is important to note that Mongolia is predominantly a Buddhist country, with over 50% of the population adhering to Tibetan Buddhism. The country also has a significant Muslim minority, as well as smaller communities of Christians and practitioners of shamanism. Hinduism is not a major religion in Mongolia, and there are very few Hindus living in the country.

That being said, there have been historical interactions between Mongols and Hindus, particularly during the Mughal Empire in India. The Mughal Emperor Akbar had a keen interest in religion and was known for his religious tolerance. He invited scholars and theologians from a variety of faiths to his court, including Hindus, and established a syncretic religion known as Din-i-Ilahi, which incorporated elements of Islam, Hinduism, and other religions.
The Mughal Empire also had significant military interactions with Mongol tribes, particularly during the reign of Aurangzeb. There are some accounts that suggest that Aurangzeb had a Mongol wife, and that she may have introduced him to Mongol religious practices.
However, it is important to note that these historical interactions do not necessarily indicate that the Mongols as a whole worship Lord Shiva. While there may be some individuals who practice Hinduism or incorporate elements of Hinduism into their religious beliefs, this is not a mainstream religious practice in Mongolia.
In conclusion, the claim that Mongols worship Lord Shiva is not accurate. While there have been historical interactions between Mongols and Hindus, particularly during the Mughal Empire in India, the majority of Mongols adhere to Tibetan Buddhism, with smaller communities of Muslims, Christians, and practitioners of shamanism. Any claims about the religious practices of a particular group should be based on reliable sources and evidence, rather than stereotypes or generalizations.