A SBAS Ionospheric Activity indicator, based in the RMS of Along Arc TEC Rate (AATR) computations has been defined by the gAGE/UPC authors in the context of previous studies on EGNOS Ionosphere. This indicator can be easily computed from GNSS data and, unlike other global indices which are related with the geomagnetic activity, it is sensible to the regional behaviour of the ionosphere. After a deep assessment done over Europe and Africa during the last Solar Cycle, this AATR indicator has been chosen as the metric to characterise the ionospheric operational conditions in the frame of ESA EGNOS activities (EGNOS V3 Mission Requirements). In this work we summarise the results of the application of the AATR indicator to the analysis of the ionospheric activity during an entire Solar Cycle in the South of Asia (SEA) Region. This region has special interest from the ionospheric point of view, because the larger Slant Total Electron Content (STEC) values and gradients experienced due to its proximity to the ionospheric equatorial anomaly.