In Jainism, time is not linear but cyclical. It moves in repeated cycles through two alternating halves:

• Utsarpiṇī (ascending): a rising era where dharma, virtue, lifespan, and worldly prosperity are said to increase.
• Avasarpinī (descending): a falling era where dharma, virtue, lifespan, and prosperity gradually decline.

Each half is subdivided into several eras (kalas), with the qualities of society changing gradually from one kal to the next. Over many cycles, the overall pattern repeats: periods of rising virtue followed by periods of decline.

We are described in Jain scriptures as currently living in the Avasarpinī half of a cycle, i.e., in the descending phase. In this era, moral values, spiritual opportunities, and lifespans are said to diminish over time, and periods of spiritual renewal become rarer. This is the context in which Mahavira’s teaching is reaffirmed as a remedy for spiritual upliftment.

Different Jain communities (Digambaras and Śvetāmbaras) sometimes differ in how they enumerate the sub-ages within each half and the exact names of those periods, but they share the core idea of time cycling between rising and falling spiritual eras.

If you’d like, I can summarize the specific names and characteristics of the kalas as described in a particular Digambara or Śvetāmbara text.