Dhrangadhra princely state was primarily located within the region known as:

Kathiawar
Halar
Sabarkantha
Mahikantha

The correct answer is Kathiawar.

Kathiawar is a peninsula in the Indian state of Gujarat. It is located in the northwestern part of the state, and is bounded by the Arabian Sea to the west, the Gulf of Kutch to the north, and the states of Rajasthan and Madhya Pradesh to the east. The peninsula is home to a number of princely states, including Dhrangadhra.

Halar is a region in the Indian state of Gujarat. It is located in the northwestern part of the state, and is bounded by the Kathiawar peninsula to the west, the Gulf of Kutch to the north, and the states of Rajasthan and Madhya Pradesh to the east. The region is home to a number of princely states, including Dhrangadhra.

Sabarkantha is a district in the Indian state of Gujarat. It is located in the northern part of the state, and is bounded by the districts of Banaskantha to the north, Mehsana to the east, Gandhinagar to the southeast, Ahmedabad to the south, and Surendranagar to the southwest. The district is home to a number of princely states, including Dhrangadhra.

Mahikantha is a region in the Indian state of Gujarat. It is located in the northwestern part of the state, and is bounded by the Kathiawar peninsula to the west, the Gulf of Kutch to the north, and the states of Rajasthan and Madhya Pradesh to the east. The region is home to a number of princely states, including Dhrangadhra.

In conclusion, the correct answer is Kathiawar.