When were mandirs first built?

Mandirs, or Hindu temples, have a long history, with their origins tracing back to ancient India around 2500 BCE, during the Indus Valley Civilization. However, the more recognizable forms of mandirs began to emerge between the 1st and 4th centuries CE, influenced by various architectural styles and religious practices. The Gupta period (approximately 320-550 CE) is often regarded as a significant time for the development of Hindu temple architecture.