Why is the South-West monsoon called 'Purvaiya' (easterly) in Bhojpur Region? How has this directional seasonal wind system influenced the cultural ethos of the region?

Why the monsoon is Purvaiya here

• The Arabian Sea branch of the south-west monsoon moves inland from the west and south-west, but the Bay of Bengal branch strikes the Eastern Himalaya and the Meghalaya–Bengal wall.
• After that strike, a large part of the Bay current is deflected up the Ganga plain as a rain-bearing easterly or south-easterly flow.
• Bhojpur, Buxar, Ara, Ballia, Ghazipur, and neighbouring districts sit where this deflected Bay current, not the dry westerly loo, brings the main kharif rain.
• Local speech therefore names the welcome wet wind Purvaiya, meaning the easterly, which is a ground name for a deflected south-west monsoon current.
• When the Purvaiya is late or weak, paddy and the flood pulse of the Ganga, Ghaghara, and Son fail together, so the name is a climate fact, not a poetic extra.

Influence on cultural ethos

• Wet-rice, sugarcane, and later wheat in a floodplain calendar shaped festivals, work songs, and the waiting for rain in Bhojpuri folk such as kajri and malhar.
• Boat culture, river ghats, and settlement on slightly higher mounds grew because the same easterly rain also means sheet flood and silt.
• Chhath and other river-facing rites in the wider region treat the sun and the river as part of a monsoon agrarian year, even when the exact date is post-monsoon.
• Language, birha, and migration songs record men leaving after harvest, which is a social answer to a densely peopled, flood-prone rice tract.
• Food, thatch, and courtyard life assume humidity and clay, so the ethos is of a wet plain, not of a rain-shadow plateau.

Way forward for the explanation

• Keep the meteorology (Bay deflection) and the culture (rice, flood, song, river rite) on the same wind, or the two parts of the question fall apart.