There are many Hindus in Arab states, many due to the migration of Indians to the oil-rich states around the Persian Gulf.
Hindu temples have been built in Bahrain, the United Arab Emirates, Kuwait, Yemen and Oman.
The estimated figures for the Hindu population in several Arab countries is as follows: 
The number of Hindus in other Arab countries, including the countries of the Levant and North Africa, is thought to be negligible, though Libya has an Indian community of about 10,000  individuals, many of whom are likely to be Hindu. It is not known whether any Hindu temples exist in these countries.
(See Hinduism by country for the sources of these figures, which may need to be adjusted.)
Historical background 
Links between Arabia and the western coast of India have been strong and persistent. Arab sailors were using the southwest monsoon winds to trade with western Indian ports before the first century CE. An Arab army conquered Sindh in 711. Arab traders settled in Kerala in the 8th century, becoming the ancestors of the Mappilas. In the opposite direction, medieval Gujaratis and other Indians traded extensively with Arab and Somali ports, including Ormuz, Socotra, Mogadishu, Merca, Barawa, Hobyo and Aden. Arab merchants were the dominant carriers of Indian Ocean trade until the Portuguese forcibly supplanted them at the end of the 15th century. Indo-Arabian links were renewed under the British Empire, when many Indians serving in the army or civil service were stationed in Arab lands such as Sudan. The current wave of Indian immigration to the Arab states of the Persian Gulf dates roughly to the 1960s. Hinduism is also one of the fastest growing religions in the Middle East. Mainly by immigration from the Indian Subcontinent. In Iran, Hinduism is the fastest growing religion, spurred mainly by interest in New Age gurus like Sri Sri Ravi Shankar and Mahesh Yogi.
Hinduism in Oman 
Oman has an immigrant Hindu minority. The number of Hindus has declined in the 20th century although it is now stable. Hinduism first came to Muscat in 1507 from Sindh. The original Hindus spoke Kutchi language. By early 19th century there were at least 4,000 Hindus in Oman, all of the intermediate merchant caste. By 1900, there numbers had plummeted to 300. In 1895 the Hindu colony in Muscat came under attack by the Ibadhis. By the time of independence, only a few dozen Hindus remained in Oman. The historical Hindu Quarters of al-Waljat and al-Banyan are no longer occupied by Hindus. Hindu temples once located in Ma'bad al Banyan and Bayt al Pir, no longer exist; the only active Hindu temples today are the Muthi Shwar temple located in Al-Hawshin Muscat, the Shiva temple located in Muttrah, and the Krishna temple located in Darsait. The only Hindu crematorium is located in Sohar, northwest of Muscat. The most prominent immigrant Hindus (Kutchi), are Khimji Ramdas, Dhanji Morarji, Ratansi Purushottam and Purushottam Toprani.