Question: Who is the spouse of the person who defeated the last song emperor of the country that is the biggest owner of US debt?

<P0-S0> According to "The Secret History of the Mongols", Chabi was the favorite wife of Kublai and a valued unofficial adviser throughout his reign. <P0-S1> She was a patron of the arts and may have played a key role in advancing the interests of the young Venetian traveler, Marco Polo. <P0-S2> It is suspected that Chabi herself may have come under Christian influence, like her mother-in-law, Sorghaghtani. <SEP> <P1-S0> the newly allied armies captured beijing on june 6. the shunzhi emperor was invested as the "son of heaven" on october 30. the manchus, who had positioned themselves as political heir to the ming emperor by defeating the rebel li zicheng, completed the symbolic transition by holding a formal funeral for the chongzhen emperor. <P1-S1> however the process of conquering the rest of china took another seventeen years of battling ming loyalists, pretenders and rebels. <P1-S2> the last ming pretender, prince gui, sought refuge with the king of burma, but was turned over to a qing expeditionary army commanded by wu sangui, who had him brought back to yunnan province and executed in early 1662. <SEP> <P2-S0> As of July 31, 2018, debt held by the public was $15.6 trillion and intragovernmental holdings were $5.7 trillion, for a total or ``National Debt ''of $21.3 trillion. <P2-S1> Debt held by the public was approximately 77% of GDP in 2017, ranked 43rd highest out of 207 countries. <P2-S2> The Congressional Budget Office forecast in April 2018 that the ratio will rise to nearly 100% by 2028, perhaps higher if current policies are extended beyond their scheduled expiration date. <P2-S3> As of December 2017, $6.3 trillion or approximately 45% of the debt held by the public was owned by foreign investors, the largest being China (about $1.18 trillion) then Japan (about $1.06 trillion). <SEP> <P3-S0> The Song dynasty is divided into two distinct periods, Northern and Southern. <P3-S1> During the Northern Song (Chinese: 北宋; 960 -- 1127), the Song capital was in the northern city of Bianjing (now Kaifeng) and the dynasty controlled most of what is now Eastern China. <P3-S2> The Southern Song (Chinese: 南宋; 1127 -- 1279) refers to the period after the Song lost control of its northern half to the Jurchen Jin dynasty in the Jin -- Song Wars. <P3-S3> During this time, the Song court retreated south of the Yangtze and established its capital at Lin'an (now Hangzhou). <P3-S4> Although the Song dynasty had lost control of the traditional ``birthplace of Chinese civilization ''along the Yellow River, the Song economy was still strong, as the Southern Song Empire contained a large population and productive agricultural land. <P3-S5> The Southern Song dynasty considerably bolstered its naval strength to defend its waters and land borders and to conduct maritime missions abroad. <P3-S6> To repel the Jin, and later the Mongols, the Song developed revolutionary new military technology augmented by the use of gunpowder. <P3-S7> In 1234, the Jin dynasty was conquered by the Mongols, who took control of northern China, maintaining uneasy relations with the Southern Song. <P3-S8> Möngke Khan, the fourth Great Khan of the Mongol Empire, died in 1259 while besieging the city of Chongqing. <P3-S9> His younger brother Kublai Khan was proclaimed the new Great Khan, though his claim was only partially recognized by the Mongols in the west. <P3-S10> In 1271, Kublai Khan was proclaimed the Emperor of China. <P3-S11> After two decades of sporadic warfare, Kublai Khan's armies conquered the Song dynasty in 1279. <P3-S12> The Mongol invasion led to a reunification under the Yuan dynasty (1271 -- 1368). <SEP> <P4-S0> the european central bank had stepped up the buying of member nations debt. <P4-S1> in response to the crisis of 2010, some proposals have surfaced for a collective european bond issue that would allow the central bank to purchase a european version of us treasury bills. <P4-S2> to make european sovereign debt assets more similar to a us treasury, a collective guarantee of the member states' solvency would be necessary. <P4-S3> [b] but the german government has resisted this proposal, and other analyses indicate that "the sickness of the euro" is due to the linkage between sovereign debt and failing national banking systems. <P4-S4> if the european central bank were to deal directly with failing banking systems sovereign debt would not look as leveraged relative to national income in the financially weaker member states.