Wikipedia
Mahdha, or Wilayat Mahdha, is an Omani territory north of Buraimi which borders the emirates of Sharjah, Ajman and Dubai. It was previously necessary to pass through Mahdha to reach the Ajmani exclave of Masfut, as well as the Dubai exclave of Hatta, a popular tourist spot for its hotel, government-run Heritage Village and the famous (although now a metalled road) Hatta track. However, a road linking Hatta to the Mileiha road now means Mahda can be bypassed. It contains the township of Rawdah and is governed from Buraimi. It was traditionally home to the Bani Ka'ab tribe.
Previously a 'soft' border, the road through Mahdha now has formal entry and exit points, requiring a photo ID such as passport or Emirates ID card for passage.
The trip to the Omani border at Hatta is a popular one for expatriates from qualifying countries performing a 'visa run' in order to renew their visit visas to the UAE. A visit visa is valid for one month, renewable at a police station up to three months but then requires an exit from the country. As a number of, mainly Western, nationalities acquire a 'visa on entry', a trip to the Hatta border post and then back results in the renewal of an expired three-month visit visa. This trip has been rendered a great deal less popular since Dubai, and the UAE in general, has reformed its immigration practices and streamlined residence visa issuance and renewal. Crossing the Omani border at Mahdha does not represent an exit from/entry to the UAE.
It is claimed the first Arab Ambassador to America, Ahmed Bin Na’man Al Ka’abi, came from Mahdah in 1840.
Likely the same district but with a different spelling of its name in English, Madha is an Omani enclave on the East Coast of the UAE which surrounds Nahwa, itself an enclave of Sharjah. This unusual arrangement is known as a counter-enclave.