For true-breeding pure Indicas, and particularly for potent Indicas, check out Afgaan 90, X18, and Deep Chunk.
Afgaan 90 is a selectively bred Afghan recently resurrected from 1990 Amsterdam seed stock.
Balkhi, a recent landrace accession from northern Afghanistan, has readily shown unusually potent plants, some over 20% THC.
In landraces, to find +10% THC individuals in first-generation populations direct from regions such as Afghanistan usually requires searching for exceptionally potent Type 1 plants. These have been idenitifed in unworked strains from the Middle East, Himalaya, and elsewhere.