(CNN)- Development in Bahrain has not been slow. In half a century, the small Gulf Island has grown from a hilly, desert landscape with 143,000 inhabitants to an overcrowded metropolis of 1.2 million residents. The most striking change, however, has been topographical.

 

Up until the 1960s, the country boasted the world's largest collection of prehistoric burial mounds -- an archaeological wonder left over from the 4,000-year-old Dilmun civilization.

 

In the decades that followed, 90% of these funerary hills fell victim to housing and infrastructure pressure, and were demolished to make room for causeways and residential estates.

 

Aside from the sheer breadth of mounds -- at their peak they numbered 76,000 -- their importance rests in their age, rarity and what they reveal about ancient society. The oldest mounds date from 2050 BC, when Dilmun (the name the Sumerians used to refer to the country) was little more than a collection of tribes, to 1750 BC, by which time it had morphed into an economic powerhouse in the region.

 

Unfortunately, the mounds have for decades been at odds with development in the country. Bahrain is only 760 square kilometers yet it has the third highest population density in the world.

 

Britta Rudolff, the managing director at Think Heritage!, an organization working with the Ministry of Culture to secure heritage status, points out that the sheer percentage of land the mounds covered makes preservation a thorny, and at times unfeasible prospect.

 

Today, development has encroached to the edge of the remaining mounds.

 

In the last five years, however, there's been a push by Bahrain's Ministry of Culture to better preserve the country's national treasures.

 

Some experts, however, argue the bulk of damage has already been done.