The thangka painting is of 35 Buddha painted by high skilled artist from Nepal. This is purely made from natural stone color and mostly Gold and Silver.
The 35 Buddhas are a set of buddhas related to the popular confessional liturgy popularly referred to as the "Confession of Downfalls of the 35 Buddhas" (The Sutra in Three Heaps).
The benefits of 35 Confessional Buddhas are extensive. According to Lama Zopa Rinpoche: “No matter what vows you might have broken (tantric root vows, or pratimoksha vows, or bodhisattva vows, or Samaya vows) no matter what negative karma you have created, everything can be purified. Out of his incomparable kindness, Guru Shakyamuni Buddha revealed different purification methods, such as prostrations to the 35 Buddhas, who are all manifestations of Guru Shakyamuni Buddha, and recitation of their names. Recitation of each Buddha’s holy name purifies tens of thousands of aeons of negative karma. If for some reason you cannot do prostrations, it is still good to at least recite holy names of the 35 Buddhas every day. No matter how heavy the negative karma you have accumulated, the Buddha has revealed a method to purify it.