Kantha is Indian/Bangladeshi. Sachiko is Japanese as is it's cousin Kogin.
They are all based on hand running stitch and traditionally used to hold two (or more) layers of fabric together for warmth and for giving a new lease of life to old fabrics, but they have all, fairly recently, evolved into art forms of embroidery.
Kantha is parallel rows of running stitch, either in straight lines like
this, or in swirling lines to echo a printed design on the fabric like
this.Sachiko from Japan has evolved into grid based designs using just running stitch. Lowena's lovely cushion is a very typical Sachiko pattern,
here are some others. White on indigo is classic.
Kogin originated in Northern Japan and has developed into a form of counted thread embroidery, typical patterns look like
these. A couple of weeks ago we did a Kogin workshp day at Craft club and I made my little bit into a needle book. Technically there's a bit of Sachiko there too, on the right hand side.